CN113330324B - Radar apparatus and signal processing method - Google Patents

Radar apparatus and signal processing method Download PDF

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Publication number
CN113330324B
CN113330324B CN201980088843.2A CN201980088843A CN113330324B CN 113330324 B CN113330324 B CN 113330324B CN 201980088843 A CN201980088843 A CN 201980088843A CN 113330324 B CN113330324 B CN 113330324B
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signal
module
transmission
target
received
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CN113330324A (en
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影目聪
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
    • G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • G01S7/354—Extracting wanted echo-signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/42—Simultaneous measurement of distance and other co-ordinates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G01S13/583—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
    • G01S13/584—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets adapted for simultaneous range and velocity measurements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • G01S7/356—Receivers involving particularities of FFT processing

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The 1 st module (1-1) generates a 1 st received signal from a reflected RF signal of the transmitted RF signal using the 1 st local oscillation signal, the 2 nd module (2-1) generates a 2 nd received signal from the reflected RF signal using a 2 nd local oscillation signal synchronized with the 1 st local oscillation signal, and the 1 st signal processor (12) calculates an angle of the target using a signal obtained by coherent integration based on the 1 st received signal and the 2 nd received signal.

Description

Radar apparatus and signal processing method
Technical Field
The present invention relates to a radar apparatus and a signal processing method.
Background
In recent years, radar devices mounted on automobiles to detect the presence of automobiles, pedestrians, or buildings around the automobiles have been developed. The radar device includes a transmitting antenna for radiating radio waves and a receiving antenna for receiving reflected waves from a target, the receiving antenna receiving radio waves radiated from the transmitting antenna, and the distance between the radar device and the target is obtained from the time from when the radio waves are radiated from the transmitting antenna until the reflected waves are received by the receiving antenna.
For example, patent document 1 describes a radar apparatus having a plurality of sub-array portions. In the radar device described in patent document 1, a plurality of sub-array portions are arranged in a dispersed manner on a plane, and each of the sub-array portions has a phased array antenna. The plurality of phased array antennas arranged on the plane are dispersed to form 1 equivalent antenna with large opening. Since the aperture length of the antenna and the angular resolution of the target are in a proportional relationship, in the radar apparatus described in patent document 1, the angular resolution of the target is improved.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open publication No. 2005-233723
Disclosure of Invention
Problems to be solved by the invention
However, in the radar apparatus described in patent document 1, the same signal is not used for the local oscillation signal for generating the transmission signal and the local oscillation signal for down-converting the reception signal in the plurality of sub-array sections arranged in a dispersed manner, and the influence of phase noise is large. Therefore, it is difficult to detect a target having a small reflected power existing around a target having a large reflected power, and there is a problem that the detection accuracy of the target is lowered. In contrast, when the same local oscillation signal is used for transmission and reception, the local oscillation signal must be distributed to each module in a wired manner, and therefore, when the frequency of the local oscillation signal is high, it is difficult to match the phases, and the output power of the local oscillation source must be increased, which causes a problem of an increase in cost. In contrast, the following structure can be considered: each module is provided with a local oscillation source, and a reference signal with a low frequency is distributed to each local oscillation source to synchronize the local oscillation sources, but in this case, the local oscillation signals of each module are different, so that the influence of phase noise still increases, and the detection accuracy of the target is deteriorated.
The present invention solves the above-described problems, and an object thereof is to provide a radar apparatus and a signal processing method as follows: it is possible to suppress the influence of phase noise and ensure detection performance with the 1 st module using the same local oscillation signal in transmission and reception, and further, to improve the angular resolution of the target with the 1 st module and the 2 nd module synchronized with the 1 st module but using different local oscillation signals in transmission and reception.
Means for solving the problems
The radar device of the present invention comprises: a 1 st module that generates a 1 st transmission signal using a 1 st local oscillation signal, transmits the 1 st transmission signal, receives a reflected signal of the 1 st transmission signal, and generates a 1 st received signal from the received reflected signal using the 1 st local oscillation signal; a 2 nd module for generating a 2 nd reception signal from the received reflection signal using a 2 nd local oscillation signal synchronized with the 1 st local oscillation signal; and a signal processor detecting a target using the 1 st received signal, for which an angle of the target is calculated using a signal obtained by coherent integration based on the 1 st received signal and the 2 nd received signal.
Effects of the invention
According to the present invention, the 1 st module generates the 1 st received signal from the reflected signal of the 1 st transmitted signal using the 1 st local oscillation signal, the 2 nd module generates the 2 nd received signal from the reflected signal of the 1 st transmitted signal using the 2 nd local oscillation signal synchronized with the 1 st local oscillation signal, and the signal processor calculates an angle of the target using a signal obtained by coherent integration based on the 1 st received signal and the 2 nd received signal for the target. Thus, the detection accuracy of the target can be ensured, and the angular resolution of the target can be improved.
Drawings
Fig. 1 is a block diagram showing the configuration of a radar apparatus according to embodiment 1.
Fig. 2 is a diagram showing configuration examples of the 1 st module, the 2 nd module, and the 3 rd module.
Fig. 3 is a block diagram showing the respective structures of the 1 st signal processor and the 2 nd signal processor.
Fig. 4 is a flowchart showing the operation of the radar apparatus according to embodiment 1.
Fig. 5 is a flowchart showing detailed processing of step ST1 of fig. 4.
Fig. 6 is a flowchart showing detailed processing of step ST2 of fig. 4.
Fig. 7 is a flowchart showing detailed processing of step ST3 and step ST4 of fig. 4.
Fig. 8A is a diagram showing a relationship between a sampling number and a hit number of a demodulated reception beat signal. Fig. 8B is a diagram showing a relationship between a distance zone number and a velocity zone number of the 1 st signal based on the distance and the velocity.
FIG. 9]Fig. 9A shows the transmission channel number n based on each transmission channel number Tx And each receiving channel number n Rx Distance and velocity of 1 st signalA graph of the relationship between the distance interval number and the speed interval number of the number. Fig. 9B is a diagram showing a relationship between the distance section number and the velocity section number of the 1 st signal after incoherent integration.
Fig. 10A is a diagram showing a relationship between a transmission channel and a reception channel in an actual antenna configuration. Fig. 10B is a diagram showing a relationship between a transmission channel and a reception channel in consideration of an actual antenna configuration and a virtual antenna configuration.
Fig. 11 is a flowchart showing detailed processing of step ST5 of fig. 4.
FIG. 12]FIG. 12A is a diagram showing the transmission channel number n of the 1 st module Tx A diagram of transmission timings of transmission RF signals in a transmission channel of=1. FIG. 12B is a diagram showing the transmission channel number n of the 1 st module Tx A diagram of transmission timings of transmission RF signals in a transmission channel of=2. Fig. 12C is a diagram showing transmission timings of the transmission RF signals of the 3 rd module 3-1. Fig. 12D is a diagram showing transmission timings of the transmission RF signals of the 3 rd module 3-2.
Fig. 13A is a flowchart showing the processing of the 1 ST module in step ST6 of fig. 4. Fig. 13B is a flowchart showing the processing of the 2 nd module in step ST6 of fig. 4.
Fig. 14 is a flowchart showing detailed processing of step ST7 and step ST8 of fig. 4.
Fig. 15A is a diagram showing an actual antenna configuration in the radar apparatus according to embodiment 1. Fig. 15B is a diagram showing an actual antenna configuration and a virtual antenna configuration in the radar apparatus according to embodiment 1.
Fig. 16 is a diagram showing a relationship between the angle of the target candidate and the power of the signal corresponding thereto in the case where the number of target candidates is 1.
Fig. 17 is a diagram showing a relationship between the angle of the target candidate and the power of the signal corresponding thereto in the case where the number of target candidates is 2.
Fig. 18A is a diagram showing an outline of a conventional radar apparatus in which a plurality of modules use the same local oscillation signal. Fig. 18B is a diagram showing an outline of a conventional radar apparatus in which a plurality of modules use different local oscillation signals, respectively. Fig. 18C is a diagram showing an outline of the radar apparatus according to embodiment 1.
Fig. 19A is a diagram showing a relationship between power of a signal corresponding to a target and a distance of the target, which is measured by a conventional radar apparatus. Fig. 19B is a diagram showing a relationship between the power of a signal corresponding to a target and the distance of the target, which is measured by the radar apparatus according to embodiment 1.
Fig. 20A is a graph showing the relationship of frequency and time for transmission and reception of signals in the 1 st module. Fig. 20B is a graph showing the phase versus time relationship between the 1 st local oscillation signal and the reflected RF signal received by the 1 st receiving section. Fig. 20C is a graph showing the phase versus time of the 2 nd local oscillation signal and the reflected RF signal received by the 2 nd receiving section.
Fig. 21 is a graph showing a relationship between a loss due to phase noise and a beat frequency.
Fig. 22 is a diagram showing a 1 st configuration example of the 1 st, 2 nd and 3 rd modules for the vehicle.
Fig. 23 is a diagram showing a 2 nd configuration example of the 1 st, 2 nd and 3 rd modules for the vehicle.
Fig. 24 is a diagram showing a 3 rd configuration example of the 1 st, 2 nd and 3 rd modules for the vehicle.
Fig. 25 is a diagram showing a 4 th configuration example of the 1 st, 2 nd and 3 rd modules for the vehicle.
Fig. 26A is a block diagram showing a hardware configuration for realizing the function of the radar apparatus according to embodiment 1. Fig. 26B is a block diagram showing a hardware configuration of software that executes functions of the radar apparatus implementing embodiment 1.
Fig. 27 is a block diagram showing the configuration of the radar apparatus according to embodiment 2.
Fig. 28 is a flowchart showing the operation of the radar apparatus according to embodiment 2.
Detailed Description
Embodiment 1
Fig. 1 is a block diagram showing the structure of a radar apparatus according to embodiment 1. For example, as shown in fig. 1, the radar apparatus according to embodiment 1 has a 1 st module 1-n MDL 2 nd Module 2-n RxEx 3 rd Module 3-n TxEx And a display 9. The display 9 for example displays the display of the 1 st module 1-n MDL And detecting the angle of the obtained target.
1 st module 1-n MDL The transmitting/receiving module transmits a high-frequency signal to the space and receives a reflected high-frequency signal obtained by reflecting the high-frequency signal by an object existing in the space. The transmission high-frequency signal is a 1 st transmission signal emitted as electromagnetic waves to the space by the radar apparatus, and is hereinafter referred to as a transmission RF signal. The reflected high-frequency signal is a reflected signal of the transmission RF signal reflected by an object existing in the space, and is referred to as a reflected RF signal. n is n MDL Is the module number, in the 1 st module 1-n MDL Is of the number N MDL In each case, the first and second modules 1-1 to 1-1 and 1-N are respectively allocated to the 1 st module 1-1 and 1 st module 1-N MDL Is a continuous numbering of (a). In FIG. 1, N MDL 1, 1 st module 1-1.
2 nd Module 2-n RxEx Is a receiving module that receives a reflected RF signal of a transmitted RF signal reflected by an object existing in a space. n is n RxEx Is the module number, in the 2 nd module 2-n RxEx Is of the number N RxEx In each case, the first and second modules 2-1 to 2-N are respectively allocated to the 2 nd module 2-1 to 2 nd module 2-N RxEx Is a continuous numbering of (a). In FIG. 1, N RxEx 1 represents 12 nd module 2-1.
3 rd Module 3-n TxEx Is a transmission module that transmits RF signals to the space radiation. n is n TxEx Is the module number, in module 3, 3-n TxEx Is of the number N TxEx In each case, the first and second modules are respectively allocated to the 3 rd module 3-1 to the 3 rd module 3-N TxEx Is a continuous numbering of (a). In FIG. 1, N TxEx 1, 1 3 rd module 3-1.
As shown in FIG. 1, 1 st module 1-n MDL The apparatus includes a 1 st transmitting unit 10, a 1 st receiving unit 11, and a 1 st signal processor 12. The 1 st transmitting unit 10 transmits RF signals 1-1-n Tx Is provided with the structural elements of the antenna 1-2-n Tx Transmitters 1-3-n Tx A transmission switching part 1-4-1, a code modulation part 1-5-1 and a 1 st local oscillation signal generation part 1-6-1.n is n Tx Is the first1 the transmission channel number of the transmission unit 10.
The number of transmission channels in the 1 st transmission unit 10 is N Tx In each case, the antennas 1-2-1 to 1-2-N are used Tx Each transmission channel of (1) to (N) Tx As the transmission channel number. Antennas 1-2-n Tx Space-radiating slave transmitters 1-3-n Tx Output transmit RF signals 1-1-n Tx 。
Fig. 1 shows a case where the 1 st transmission unit 10 has 2 transmission channels. The transmission RF signal 1-1-1 is a signal outputted from the transmitter 1-3-1 to the antenna 1-2-1 and radiated to the space by the antenna 1-2-1, and the transmission RF signal 1-1-2 is a signal outputted from the transmitter 1-3-2 to the antenna 1-2-2 and radiated to the space by the antenna 1-2-2.
Transmitters 1-3-n Tx The RF signal is input from the code modulation unit 1-5-1 via the transmission switching unit 1-4-1 and transmitted by using the antenna 1-2-n Tx The inputted transmission RF signal is transmitted to the space. The transmission switching unit 1-4-1 transmits data from the transmitters 1-3-1 to 1-3-N Tx Is switched to a transmitter to transmit the RF signal. For example, the transmission switching section 1-4-1 alternately switches the transmitters 1-3-1 and 1-3-2, thereby alternately radiating the transmission RF signal 1-1-1 and the transmission RF signal 1-1-2 to the space.
The code modulation section 1-5-1 uses the 1 st local oscillation signal generated by the 1 st local oscillation signal generation section 1-6-1 and the transmission channel number n Tx Generates a transmission channel number n by modulating a code in a transmission channel of (a) Tx Is used for transmitting RF signals 1-1-n Tx . The 1 st local oscillation signal generating section 1-6-1 generates the 1 st local oscillation signal, and outputs the generated 1 st local oscillation signal to the code modulating section 1-5-1 and the receiver 1-8-n Rx,nMDL 。
The 1 st receiving section 11 has antennas 1-7-n Rx,nMDL Receivers 1-8-n Rx,nMDL And A/D converters 1-9-n Rx,nMDL Receiving transmitted RF signals 1-1-n reflected by objects present in space Tx Is provided for the reflected RF signal a. n is n Rx,nMDL The 1 st reception unit 11 receives the channel number. For example, the number of reception channels in the 1 st reception unit 11 is N Rx,nMDL In each case, the antennas 1-7-1 to 1-7-N are referred to Rx,nMDL Sequentially allocating 1 to N to the reception channels of (a) Rx,nMDL As the receive channel number.
Antennas 1-7-n Rx,nMDL Receiving the reflected RF signal A and outputting the received reflected RF signal A to the receivers 1-8-n Rx,nMDL . Receivers 1-8-n Rx,nMDL For antennas 1-7-n Rx,nMDL The received reflected RF signal A is subjected to signal processing, and the signal after the signal processing is output to the A/D converter 1-9-n Rx,nMDL . For example, receivers 1-8-n Rx,nMDL Down-converting the reflected RF signal a using the 1 st local oscillation signal, filtering the down-converted signal using a band filter, amplifying the intensity of the signal filtered by the band filter, phase detecting the amplified signal, and generating a reception channel number n using the phase detected signal Rx,nMDL A reception beat signal of a reception channel of (a).
A/D converters 1-9-n Rx,nMDL Will be received from receivers 1-8-n Rx,nMDL The output signal is converted from an analog signal to a digital signal, and a reception beat signal of the digital signal is generated using the signal converted to the digital signal. By A/D converters 1-9-n Rx,nMDL The reception beat signal converted into the digital signal is a reception signal for detecting the target candidate and calculating the angle of the target candidate, and is output to the 1 st signal processor 12.
1 st module 1-n MDL Reception by 1 st Module 1-n MDL The reception beat signal generated by the reflected RF signal of the transmitted transmission RF signal (1 st transmission signal) is the 1 st reception signal. In addition, the 2 nd module 2-n RxEx Reception by 1 st Module 1-n MDL Reflected RF signals of transmitted RF signals or by the 3 rd module 3-n TxEx The reception beat signal generated by the reflected RF signal of the transmitted transmission RF signal (3 rd transmission signal) is the 2 nd reception signal. Further, 1 st module 1-n MDL Receiving the data from the 3 rd module 3-n TxEx The reception beat signal generated by the reflected RF signal of the transmitted transmission RF signal is the 3 rd reception signal. The 1 st received signal is used to detect the target. Further, the 1 st received signal, the 2 nd received signal, or the 3 rd received signal is used to calculate the angle of the target.
1 st letter The number processor 12 is a signal processor as follows: detecting a target candidate using the reception beat signal output from the 1 st receiving section 11 using the signal obtained by using the reception beat signal output from the 1 st receiving section 11 and the signal obtained by the 2 nd module 2-n RxEx The angle of the target candidate is calculated from the signal obtained by coherent integration of the obtained reception beat signal. For example, the 1 st signal processor 12 calculates the 1 st signal based on the distance and the speed of the target candidate using the reception beat signal output from the 1 st reception section 11. The 1 st signal processor 12 detects a target candidate using the calculated 1 st signal. Further, the 1 st signal processor 12 is directed to the 3 rd module based 3-n TxEx Each of the transmission channels and 2 nd module 2-n RxEx Distance and speed of target candidate for each receive channel, and 3-n based on 3 rd module 3-n TxEx Each of the transmission channels and 1 st module 1-n MDL The 3 rd signal of the distance and the speed of the target candidate for each reception channel, coherently integrating according to the arrival phase difference corresponding to the arrival angle candidate of the target candidate, and calculating the angle of the target candidate using the signal obtained by the coherent integration. In addition, the arrival phase difference corresponding to the arrival angle candidate of the target candidate is according to the 1 st module 1-n MDL And the 2 nd module 2-n RxEx An incoming phase difference due to the positional relationship of (a) and (b).
As shown in FIG. 1, the 2 nd module 2-n RxEx Has a 2 nd receiving section 20 and a 2 nd signal processor 21. The 2 nd receiving unit 20 is a component for receiving the reflected RF signal A, and has a 2 nd local oscillation signal generating unit 2-6-1 and an antenna 2-7-n Rx,nRxEx Receivers 2-8-n Rx,nRxEx And A/D converters 2-9-n Rx,nRxEx 。n Rx,nRxEx The reception channel number of the 2 nd reception unit 20. The number of reception channels in the 2 nd reception unit 20 is N Rx,nRxEx In the case of each antenna, the antennas 2-7-1 to 2-7-N are connected to each other Rx,nRxEx Respective receiving channels are allocated in sequence 1 to N Rx,nRxEx As the receive channel number. The 2 nd local oscillation signal generating section 2-6-1 generates the 2 nd local oscillation signal and outputs the generated 2 nd local oscillation signal to the receiver 2-8-n Rx,nRxEx . The 2 nd local oscillator signal is synchronized with the 1 st local oscillator signal.
Antennas 2-7-n Rx,nRxEx Receiving the reflected RF signal A and outputting the received reflected RF signal A to the receiver 2-8-n Rx,nRxEx . Receivers 2-8-n Rx,nRxEx For the antenna 2-7-n Rx,nRxEx The received reflected RF signal A is subjected to signal processing, and the signal after signal processing is output to the A/D converter 2-9-n Rx,nRxEx . Receivers 2-8-n Rx,nRxEx For example, the reflected RF signal a is down-converted using the 2 nd local oscillation signal, the down-converted signal is filtered using the band filter, the intensity of the signal filtered by the band filter is amplified, the amplified signal is phase-detected, and then the reception channel number n is generated using the phase-detected signal Rx,nRxEx A reception beat signal of a reception channel of (a).
A/D converter 2-9-n Rx,nRxEx Will be received from receivers 2-8-n Rx,nRxEx The output signal is converted from an analog signal to a digital signal, and a reception beat signal of the digital signal is generated using the signal converted to the digital signal. By A/D converters 2-9-n Rx,nRxEx The reception beat signal converted into the digital signal is a 2 nd reception signal for calculating the angle of the target candidate, and is output to the 2 nd signal processor 21.
The 2 nd signal processor 21 generates a 2 nd signal for calculating the angle of the target candidate from the reception beat signal output from the 2 nd reception section 20. For example, the 2 nd signal processor 21 uses the slave A/D converter 2-9-n Rx,nRxEx The output reception beat signal calculates a 2 nd signal based on the distance and the speed of the target candidate. The 2 nd signal is output from the 2 nd signal processor 21 to the 1 st signal processor 12.
As shown in FIG. 1, the 3 rd module 3-n TxEx Has a 3 rd transmitting unit 30. The 3 rd transmitting unit 30 radiates the RF signals 3-1-n Tx,nTxEx Is provided with the structural elements of the antenna 3-2-n Tx,nTxEx Transmitters 3-3-n Tx,nTxEx Code modulation section 3-5-1 and 3 rd local oscillation signal generation section 3-6-1.n is n Tx,nTxEx The transmission channel number of the 3 rd transmission unit 30.
The number of transmission channels in the 3 rd transmission unit 30 is N Tx,nTxEx In the case of the number of antennas 3-2-1 to 3-2-N Tx,nTxEx Each of which is a single pieceSequentially allocating 1 to N to transmission channels of (a) Tx,nTxEx As the transmission channel number. Antennas 3-2-n Tx,nTxEx Space-radiating slave transmitters 3-3-n Tx,nTxEx Outgoing transmit RF signals 3-1-n Tx,nTxEx . Fig. 1 shows a case where the 3 rd transmission unit 30 has 1 transmission channel. The transmission RF signal 3-1-1 is a signal outputted from the transmitter 3-3-1 to the antenna 3-2-1 and radiated to space by the antenna 3-2-1.
Transmitters 3-3-n Tx,nTxEx Using antennas 3-2-n Tx,nTxEx Transmitting the modulated data to the space by the code modulation unit 3-5-n Tx,nTxEx The generated transmit RF signal. Code modulation section 3-5-n Tx,nTxEx Using the 3 rd local oscillation signal generated by the 3 rd local oscillation signal generating section 3-6-1 and the transmission channel number n Tx,nTxEx Modulation code generation in transmission channel of (c) transmission channel number n Tx,nTxEx Is used for transmitting RF signals 3-1-n Tx,nTxEx . The 3 rd local oscillation signal generating section 3-6-1 generates a 3 rd local oscillation signal, and outputs the generated 3 rd local oscillation signal to the code modulating section 3-5-1.
Fig. 2 is a diagram showing an example of the arrangement of the 1 st module 1-1, the 2 nd modules 2-1 to 2-4 and the 3 rd modules 3-1, 3-2. In FIG. 2, the number of modules N of the 1 st module MDL 1, 1 st module 1-1, number of transmission channels N Tx,nMDL 2, 1 st module 1-1 receives the number N of channels Rx,nMDL 4. In addition, the number of modules N of the 2 nd module RxEx 4, the number N of the receiving channels of the 2 nd module 2-1 to 2-4 respectively Rx,nRxEx 4. Number of modules N of the 3 rd module TxEx 2, 3 rd module 3-1 and 3 rd module 3-2 each transmit channel number N Tx,nTxEx 1.
FIG. 2 shows the formation of the 3 rd module 3-1 having the antenna 3-2-1, the 2 nd module 2-1 having the antenna 2-7-1-2-7-4, the 2 nd module 2-2 having the antenna 2-7-1-2-7-4, the 1 st module 1-1 having the antenna 1-2-1, the 1 st module 1-1 having the antenna 1-7-1-7-4 the antennas 1-2-2 and 2-7-1 to 2-7-4 of the 1 st module 1-1 and 2-3 of the 2 nd module 2-3, and the antennas 2-7-1 to 2-7-4 of the 2 nd module 2-4 and the antennas 3-2-2 of the 3 rd module 3-2 are arranged in a linear array in order.
Fig. 3 is a block diagram showing the respective structures of the 1 st signal processor 12 and the 2 nd signal processor 21. As shown in fig. 3, the 1 st signal processor 12 includes a 1 st separating unit 120, a 1 st signal generating unit 121, a noncoherent integrating unit 122, a target candidate detecting unit 123, a 1 st coherent integrating unit 124, a 2 nd coherent integrating unit 125, and an angle calculating unit 126. The 2 nd signal processor 21 has a 2 nd separation section 210 and a 2 nd signal generation section 211.
The 1 st separating unit 120 receives the reception beat signal of each reception channel from the 1 st receiving unit 11, and separates the reception beat signal of each reception channel into reception beat signals of each transmission channel. Thereby, a reception beat signal for each transmission channel and each reception channel is obtained. The 1 st signal generating section 121 generates a 1 st signal based on the distance and speed of the target candidate using the reception beat signal of each transmission channel and each reception channel.
The incoherent integration unit 122 performs incoherent integration on the 1 st signal generated by the 1 st signal generation unit 121, and outputs a signal obtained by incoherent integration to the target candidate detection unit 123. The target candidate detection unit 123 detects a target candidate from the intensity of the signal obtained by the incoherent integration unit 122. For example, the distance and speed of the target candidate are detected by the target candidate detecting section 123.
The 1 st coherent integration section 124 is directed to 1 st module 1-n MDL The 1 st signal of each transmission channel and each reception channel related to each target candidate is coherently integrated based on the arrival phase difference corresponding to the arrival angle candidate of the target candidate. The incoming phase difference corresponds to the phase difference of the signals between the channels.
The 2 nd coherent integration portion 125 performs based on the data obtained from the 1 st module 1-n MDL The generated received signal and the received signal generated by the 2 nd module 2-n RxEx Coherent integration of the generated received signal. For example, the 2 nd coherent integration unit 125 performs coherent integration on the 2 nd signal based on the distance and speed of each target candidate of each of the transmission channels of the 3 rd module and each of the reception channels of the 2 nd module, and the 3 rd signal based on the distance and speed of each of the target candidates of each of the transmission channels of the 3 rd module and each of the reception channels of the 1 st module, based on the arrival phase differences corresponding to the arrival angle candidates of the target candidates. The arrival phase difference corresponds to the phase difference according to the 1 st module 1-n MDL And the 2 nd module 2-n RxEx An incoming phase difference due to the positional relationship of (a) and (b).
The angle calculation unit 126 receives signals obtained by coherent integration with respect to each target candidate from the 2 nd coherent integration unit 125, and calculates the angle of the target candidate from the intensity of the received signals. The angle of the target candidate calculated by the angle calculation unit 126 is displayed on the display 9, for example.
In addition, the 1 st module 1-n shown in FIG. 1 MDL Has a 1 st signal processor 12, however, 1 st module 1-n MDL And the 1 st signal processor 12 may also be different devices. Likewise, module 2-n RxEx And the 2 nd signal processor 21 may also be different devices. In addition, the 1 st module 1-n MDL The 1 st signal processor 12 includes a 1 st separation unit 120, a 1 st signal generation unit 121, and an incoherent integration unit 122, and includes a target candidate detection unit 123, a 1 st coherent integration unit 124, a 2 nd coherent integration unit 125, and an angle calculation unit 126.
In the 2 nd signal processor 21, the 2 nd separating unit 210 receives the reception beat signal of each reception channel from the 2 nd receiving unit 20, and separates the reception beat signal of each reception channel into the reception beat signal of each transmission channel. Thereby, a reception beat signal of each reception channel in the 2 nd block is obtained. The 2 nd signal generating unit 211 performs discrete fourier transform on the reception beat signal of each reception channel, thereby generating a 2 nd signal corresponding to the distance and speed of the target candidate in the 2 nd block.
Next, an operation of the radar apparatus according to embodiment 1 will be described.
Fig. 4 is a flowchart showing the operation of the radar apparatus according to embodiment 1, and shows a signal processing method of the radar apparatus according to embodiment 1.
First, 1 st Module 1-n MDL An RF signal is transmitted to the space radiation (step ST 1). For example, 1 st Module 1-n MDL The 1 st transmission unit 10 transmits RF signals to the space. When an object exists in space, the transmitted RF signal is reflected by the object and returned to the radar apparatus. 1 st module 1-n MDL The 1 ST receiving unit 11 receives the reflected RF signal of the transmission RF signal, and generates a reception beat signal from the reflected RF signal using the 1 ST local oscillation signal (step ST 2).
Next, the 1 ST signal processor 12 detects a target candidate using the reception beat signal generated by the 1 ST reception section 11 (step ST 3). For example, the 1 st signal processor 12 generates a signal based on the 1 st module 1-n using the reception beat signal inputted from the 1 st reception section 11 MDL The 1 st signal of the distance and speed of the target candidate for each transmit channel and each receive channel. The 1 st signal processor 12 performs incoherent integration on the generated 1 st signal, and calculates the distance and speed of the target candidate from the intensity of the signal obtained by the incoherent integration.
Next, the 1 st signal processor 12 targets the 1 st module 1-n associated with each target candidate MDL The 1 ST signal of each transmission channel and each reception channel is coherently integrated based on the arrival phase difference corresponding to the arrival angle candidate of the target candidate (step ST 4). The treatment is to the 1 st module 1-n MDL Inter-channel coherent integration performed on the signal corresponding to the interval in which the target candidate is detected.
Next, module 3-n TxEx The RF signal is transmitted to the space radiation (step ST 5). For example, 3 rd Module 3-n TxEx The 3 rd transmitting unit 30 transmits RF signals to the space. However, in step ST5, the 1 ST module 1-n may be MDL The 1 st transmission unit 10 transmits RF signals to the space. In this case, the radar apparatus according to embodiment 1 may not include the 3 rd module 3-n TxEx 。
Next, 1 st module 1-n MDL The 1 st receiving part 11 receives the data of the 3 rd module 3-n TxEx A reflected RF signal of the transmitted RF signal is generated from the reflected RF signal using the 1 st local oscillation signal. Further, the 2 nd module 2-n RxEx The 2 nd receiving part 20 receives the signal of the 3 rd module 3-n TxEx A reflected RF signal of the transmitted RF signal is generated from the reflected RF signal using a 2 nd local oscillator signal synchronized with the 1 st local oscillator signal. The processing up to this point is step ST6.
2 nd Module 2-n RxEx Has a 2 nd signal processor 21 according to the 3 rd module 3-n TxEx A2 nd signal based on the distance and the speed of each target candidate of each transmission channel of the 3 rd module and each reception channel of the 2 nd module is generated from the reception beat signal calculated from the reflected RF signal of the transmitted transmission RF signal. The 2 nd signal is from the 2 nd module 2-n RxEx To the 1 st signal processor 12.
The 1 st signal processor 12 generates a 3 rd based module 3-n TxEx Each of the transmission channels and 1 st module 1-n MDL For the 3 rd signal of the distance and speed of the respective target candidate of each receiving channel, for the 2 nd module 2-n RxEx The obtained 2 nd signal and the generated 3 rd signal are coherently integrated based on the arrival phase difference corresponding to the arrival angle candidate of the target candidate (step ST 7). Thus, in the 1 st module 1-n distributed MDL And the 2 nd module 2-n RxEx And performs coherent integration of the signal.
Finally, the 1 ST signal processor 12 calculates the angle of the target candidate using the signals obtained by coherent integration with respect to each target candidate (step ST 8). Information about the angle of the target candidate calculated by the 1 st signal processor 12 is displayed on the display 9.
Next, details of the signal processing method according to embodiment 1 will be described.
Fig. 5 is a flowchart showing detailed processing of step ST1 of fig. 4. In 1 st Module 1-n MDL In the 1 st local oscillation signal generating section 1-6-1, the 1 st local oscillation signal L is generated 1,nMDL (n Tx H, t), the 1 st local oscillation signal L to be generated 1,nMDL (n Tx H, t) are output to the code modulation section 1-5-1 and the receiver 1-8-n Rx,nMDL (step ST1 a).
1 st local oscillation signal L 1,nMDL (n Tx H, t) is represented by the following formula (1). In the following formula (1), j is an imaginary unit. n is n MDL Is 1 st module 1-n MDL Module number, N MDL Is 1 st module 1-n MDL Is a module number of (a) in the module number. In the 1 st module 1-1 shown in FIG. 1, n MDL And N MDL 1.n is n Tx Is 1 st module 1-n MDL Transmission channel number, N Tx Is 1 st module 1-n MDL Is used for the transmission channel number. n is n Tx Is 1 or 2, N Tx 2.
Figure GDA0003160005870000111
In the above-mentioned formula (1),
Figure GDA0003160005870000112
is 1 st module 1-n MDL The transmission channel number n of (2) Tx Initial phase of the 1 st local oscillator signal in the transmission channel. />
Figure GDA0003160005870000113
Is 1 st module 1-n MDL The transmission channel number n of (2) Tx Phase noise of the 1 st local oscillation signal in the transmission channel. H is hit number, and H is hit number.
In the above formula (1), A L Is the amplitude of the 1 st local oscillation signal, f 0 Is the transmission frequency of the transmitted RF signal. B (B) 0 Is the modulation band of the transmitted RF signal, T 0 Is the modulation time, T 1 The time until the next modulation is taken, and t is the time. T (T) chp Is to transmit RF signals 1-1-n Tx The transmission repetition period of (2) can be expressed by the following equation. T (T) Tx The transmission repetition period can be represented by the following expression (3).
T chp ＝(N Tx -1)T Tx ···(2)
T Tx ＝T 0 +T 1 ···(3)
Next, the code modulation section 1-5-1 generates the 1 st local oscillation signal L from the 1 st local oscillation signal generation section 1-6-1 1,nMDL (n Tx H, t) are code modulated (step ST2 a). In the code modulation process, the code modulation unit 1-5-1 pairs the 1 st local oscillation signal L 1,nMDL (n Tx H, t) to generate a transmission channel number n of the 1 st module 1-1 Tx Is a transmission RF signal Tx (n Tx H, t). By the first pair ofTransmission channel number n of 1 module 1-1 Tx 1 st local oscillator signal L in a transmission channel of (a) 1,nMDL (n Tx H, t) performs code modulation to suppress interference between transmission channels and interference of radio waves from outside.
As an example of the code modulation, the code modulation in which a cyclic code is added as a pseudo random number will be described.
The code modulation unit 1-5-1 makes a preset cyclic code C according to the following formula (4) 0 (h) With the transmission channel number n in the 1 st module 1-1 Tx Is set in the transmission channel (n) Tx ) And performing cyclic shift. By performing this cyclic shift, the transmission channel number n in the 1 st module 1-1 is generated Tx Modulation Code of transmission channel of (a) 1 (n Tx H). In addition, in cyclic code C 0 (h) In (a), an M sequence (Maximal length sequence), a Gold sequence, or a spreading sequence may also be used.
Figure GDA0003160005870000121
Next, the 1 st local oscillation signal L is used by the code modulation section 1-5-1 1,nMDL (n Tx H, t) and 1 st module 1-n MDL Transmission channel number n in (a) Tx Modulation Code of transmission channel of (a) nMDL (n Tx H), generating a transmission channel number n according to the following formula (5) Tx Transmit RF signal Tx in a transmit channel of (a) 1,nMDL (n Tx H, t). The transmission RF signal Tx generated by the code modulation section 1-5-1 1,nMDL (n Tx H, t) is output to the transmission switching section 1-4-1.
Figure GDA0003160005870000122
Transmission switching units 1-4-n Tx,nMDL According to 1 st module 1-n MDL The transmission channel number n of (2) Tx Is to 1 st module 1-n MDL The transmission channel number n of (2) Tx Transmit RF signal Tx in a transmit channel of (a) 1,nMDL (n Tx H, t) output to the hairConveyor 1-3-n Tx . Transmitters 1-3-n Tx The slave transmission switching units 1-4-n Tx,nMDL Input transmit RF signal Tx 1,nMDL (n Tx H, t) output to antennas 1-2-n Tx . Antennas 1-2-n Tx Space-oriented radiation and 1 st module 1-n MDL Is transmitted channel n of (2) Tx Corresponding transmit RF signal Tx 1,nMDL (n Tx H, t) (step ST3 a). In FIG. 1, N Tx 2, so that the antennas 1-2-1 and 1-2-2 alternately radiate the transmission RF signal Tx to the space 1,nMDL (n Tx ,h,t)。
Fig. 6 is a flowchart showing detailed processing of step ST2 of fig. 4.
The transmission RF signal radiated to the space is reflected by a target existing in the space to become a reflected RF signal a. Reflected RF signal A is incident on 1 st module 1-n MDL Antennas 1 to 7 to n in the 1 st receiving unit 11 Rx,nMDL . Antennas 1-7-n Rx,nMDL The incident reflected RF signal a is received (step ST1 b).
By antennas 1-7-n Rx,nMDL The received reflected RF signal A as 1 st module 1-n MDL Is received on channel n of (2) Rx,nMDL In a receiving RF signal Rx 1,nMDL (n Tx ,n Rx H, t) is output to the receivers 1-8-n Rx,nMDL . Receiving RF signals Rx 1,nMDL (n Tx ,n Rx H, t) is represented by the following formula (6). In the following formula (6), A R Is the amplitude of the received RF signal. R is R 0 Is the initial target relative distance, which is the initial value of the target's relative distance. v is the target relative velocity and θ is the target angle. c is the speed of light and t' is the time within 1 hit.
Figure GDA0003160005870000131
In the above-mentioned formula (6),
Figure GDA0003160005870000132
is 1 st module 1-n MDL The transmission channel number n of (2) Tx The phase difference in the transmission channel of (a) can be expressed by the following equation7) And (3) representing. />
Figure GDA0003160005870000133
Is 1 st module 1-n MDL Is the reception channel number n of (2) Rx,nMDL The phase difference in the reception channel of (2) can be expressed by the following equation (8).
Figure GDA0003160005870000141
Figure GDA0003160005870000142
Then, the receivers 1-8-n Rx,nMDL Using 1 st local oscillator signal L 1,nMDL (n Tx H, t), receives an RF signal Rx 1,nMDL (n Tx ,n Rx H, t) down-conversion (step ST2 b). Then, the receivers 1-8-n Rx,nMDL The down-converted signal is filtered using a band filter, the intensity of the signal passing through the band filter is amplified, and then phase detection is performed. By these processes, the 1 st module 1-n is generated MDL Is the reception channel number n of (2) Rx,nMDL Reception beat signal V 'in reception channel of (a)' 1,nMDL (n Tx ,n Rx ,h,t)。
Receiving beat signal V' 1,nMDL (n Tx ,n Rx H, t) can be expressed by the following formula (9) from the receivers 1-8-n Rx,nMDL Outputs to A/D converters 1-9-n Rx,nMDL . In the following formula (9), A V Is to receive the beat signal V' 1,nMDL (n Tx ,n Rx H, t). P is p nis (M Tx,MDL ,M Rx,MDL ) Is phase noise. Further, M Tx,MDL Is the module number M of the module generating the 1 st local oscillation signal for generating the transmission RF signal Rx,MDL Is the module number of the module that generates the 1 st local oscillator signal for down-converting the received RF signal.
Figure GDA0003160005870000151
In the above formula (9), the phase noise p in the 1 st transmitting unit 10 and the 1 st receiving unit 11 nis (M Tx,MDL ,M Rx,MDL ) Represented by the following formula (10).
Figure GDA0003160005870000152
Further, the phase noise p in the 1 st transmitting unit 10 and the 2 nd receiving unit 20 nis (M Tx,MDL ,M Rx,MDL ) Represented by the following formula (11).
Figure GDA0003160005870000153
A/D converters 1-9-n Rx,nMDL 1 st module 1-n MDL Is the reception channel number n of (2) Rx,nMDL Reception beat signal V 'in reception channel of (a)' 1,nMDL (n Tx ,n Rx H, t) from an analog signal to a digital signal, thereby generating a reception beat signal V represented by the following formula (12) 1,nMDL (n Tx ,n Rx H, m) (step ST3 b).
Figure GDA0003160005870000161
Here, the beat signal V is received 1,nMDL (n Tx ,n Rx H, m) is 1 st module 1-n MDL Is the reception channel number n of (2) Rx,nMDL The 1 st reception beat signal in the reception channel of (a). The 1 st reception beat signal is a 1 st reception signal for detecting a target. In the above formula (12), Δt is the modulation time T 0 Sampling intervals within. m is the modulation time T 0 The sample number of the internally sampled received beat signal. M is the modulation time T 0 The number of samples of the received beat signal. In the above formula (12), Δt is contained 2 And 1/c 2 Is approximately represented by the term(s).
Fig. 7 is a flowchart showing detailed processing of step ST3 and step ST4 of fig. 4. The 1 st separation unit 120 of the 1 st signal processor 12 uses the 1 st module 1-n MDL The transmission channel number n of (2) Tx Modulation Code set in transmission channel of (a) 1 (n Tx H), demodulating the 1 st reception beat signal according to the following expression (13). The demodulated 1 st received beat signal is separated into 1 st blocks 1-n MDL Signals of each transmission channel and each reception channel (step ST1 c). Thereby generating the 1 st module 1-n MDL Transmission channel number n in (a) Tx And receiving channel number n Rx Corresponding reception beat signal V 1,nMDL,C (n Tx ,n Rx H, m), the generated reception beat signal V 1,nMDL,C (n Tx ,n Rx H, m) is output to the 1 st signal generating section 121.
Figure GDA0003160005870000162
Next, the 1 st signal generating unit 121 generates a reception beat signal V demodulated by the 1 st separating unit 120 1,nMDL,C (n Tx ,n Rx H, m) to a discrete fourier transform, thereby generating a block 1-n based on block 1 MDL The 1 ST signal of the distance and speed of the target candidate of each transmission channel and each reception channel (step ST2 c). For example, at n MDL When 1 is found, the 1 st signal generating unit 121 performs discrete fourier transform according to the following equation (14). Thereby, the transmission channel number n corresponding to the 1 st module 1-1 is generated Tx And receiving channel number n Rx Corresponding 1 st signal f b,1,nMDL (n Tx ,n Rx Q, k). q is a speed section number, and k is a distance section number. Fig. 8A is a diagram showing a demodulated reception beat signal V 1,nMDL,C (n Tx ,n Rx H, m) and hit number. FIG. 8B is a graph showing the 1 st signal f based on distance and speed b,1,nMDL (n Tx ,n Rx Q, k) and a velocity interval number. As shown in FIG. 8A and FIG. 8B, the following formula (14) is usedThe received beat signals of the sample number m and the hit number h are subjected to discrete fourier transform to generate a 1 st signal based on distance and speed from which the distance information and the speed information of the target candidate a can be obtained. Further, the signal-to-noise ratio SNR (Signal to Noise Ratio) of the radar device of embodiment 1 improves by 10log 10 (HM), the detection performance of the target is improved. Instead of the discrete fourier transform, a fast fourier transform (FFT; fast Fourier Transform) may also be used. In the case of using FFT, it is possible to achieve low computation and high speed, and a radar device with low cost and shortened processing time can be obtained.
Figure GDA0003160005870000171
Next, the incoherent integration unit 122 performs incoherent integration on the 1 ST signal generated by the 1 ST signal generation unit 121 (step ST3 c). For example, at n MDL In the case of 1, the incoherent integration section 122 performs the correlation with the transmission channel number n in the 1 st block 1-1 Tx And receiving channel number n Rx Corresponding 1 st signal f b,1,nMDL (n Tx ,n Rx Q, k), non-coherent integration is performed according to the following equation (15). Generating a signal f by the incoherent integration b,1,nMDL,inch (q, k), the generated signal f b,1,nMDL,inch (q, k) is output from the incoherent integration section 122 to the target candidate detection section 123.
Fig. 9A shows the transmission channel number n based on each transmission channel number Tx And each receiving channel number n Rx Distance and velocity of 1 st signal f b,1,nMDL (n Tx ,n Rx Q, k) and a velocity interval number. The non-coherent integration unit 122 is input with the transmission channel number n shown in fig. 9A Tx And receiving channel number n Rx Corresponding 1 st signal f b,1,nMDL (n Tx ,n Rx Q, k). The 1 st signal is a signal based on the distance and speed of the target candidate a. The 1 st signal is superimposed with a noise component b. FIG. 9B is a graph showing the 1 st signal f after incoherent integration b,1,nMDL,inch (q, k) dependence of distance interval number on velocity interval numberIs a drawing. The incoherent integration section 122 performs, as shown in the following equation (15), on the plurality of 1 st signals f b,1,nMDL (n Tx ,n Rx Q, k), the power, that is, the signal intensity is integrated, and thereby, as shown in fig. 9B, the noise component B is averaged, and a radar apparatus with improved target detection performance can be obtained.
Figure GDA0003160005870000181
The target candidate detection unit 123 generates a signal f based on incoherent integration b,1,nMDL,inch (q, k), and the distance and speed of the target candidate are calculated (step ST4 c). In the detection of target candidates, CA-CFAR (Cell Average Constant False Alarm Rate), for example, is used. The target candidate detecting unit 123 determines the target candidate number n tgt 1 st module 1-n corresponding to target candidate of (2) MDL Transmission channel n in (a) Tx And receiving channel n Rx 1 st signal f of (2) b,1,nMDL (n Tx ,n Rx ,q ntgt ,k ntgt ) Speed interval number q, which is the sampling number in the speed direction ntgt Distance interval number k, which is the sampling number in the distance direction ntgt Outputs it to the 1 st coherent integration section 124 and the 2 nd module 2-n RxEx A 2 nd signal processor 21 of (c). Target candidate number n tgt Is a consecutive number assigned per target candidate.
The 1 st coherent integration unit 124 performs the correlation with the target candidate number n tgt Based on the arrival phase difference corresponding to the arrival angle candidate of the target candidate, the inter-channel coherent integration is performed according to the following equation (16) (step ST5 c). However, the 1 st coherent integration unit 124 uses the target candidate number n when there is an influence of the target movement, which is the doppler frequency between transmission channels tgt Speed interval number q ntgt After suppressing the influence of the velocity, the process of the following formula (16) is performed. The 1 st coherent integration unit 124 integrates the 1 st signal f b,1,nMDL (n Tx ,n Rx ,q ntgt ,k ntgt ) Performing inter-channel coherent integrationThereby, the target candidate number n is generated tgt Signal R corresponding to target candidate of (2) 1,ch (n θ ,q ntgt ,k ntgt ). Signal R 1,ch (n θ ,q ntgt ,k ntgt ) The 1 st coherent integration unit 124 outputs the signal to the display 9, and the signal is displayed on the display 9.
Figure GDA0003160005870000191
In the above formula (16), N θ Is the number of hypothetical target angles, n θ Is a target angle number assigned to the virtual target angle. In addition, in the case of the optical fiber,
Figure GDA0003160005870000192
is with the target angle number n θ 1 st module 1-n related to target angle of (c) MDL The transmission channel number n of (2) Tx The phase difference in the transmission channel of (a) is represented by the following equation (17). Further, the processing unit is used for processing the data,
Figure GDA0003160005870000193
is with the target angle number n θ 1 st module 1-n related to target angle of (c) MDL Is the reception channel number n of (2) Rx,nMDL The arrival phase difference in the reception channel of (2) is represented by the following equation (18).
Figure GDA0003160005870000194
Figure GDA0003160005870000195
In the above formulas (16) to (18), the target angle θ and the target angle number n θ Target angle θ 'of (2)' nθ In the case of coincidence, with the target candidate number n tgt Target candidate related signal R of (2) 1,ch (n θ ,q ntgt ,k ntgt ) Is coherently integrated, signal power is shownMaximum value. Namely, by the method of the 1 st module 1-n MDL The signals of each transmission channel and each reception channel are coherently integrated, and the power of the coherently integrated signals is increased. Therefore, by using this signal, a radar device with improved detection performance of the target can be obtained.
Fig. 10A is a diagram showing a relationship between a transmission channel and a reception channel in an actual antenna configuration. Fig. 10B is a diagram showing a relationship between a transmission channel and a reception channel in consideration of an actual antenna configuration and a virtual antenna configuration. In fig. 10A and 10B, the antennas denoted by reference numerals (1) and (2) are antennas included in the 1 st transmission unit 10, and correspond to transmission channels, respectively. The antenna denoted by the reference numeral (3) corresponds to the reception channel, and the antenna is the antenna of the 1 st reception unit 11. As shown in fig. 10A, in the actual array in which the antennas denoted by (3) are actually arranged, the antenna opening length is D.
The 1 st signal processor 12 coherently integrates the signals of each of the transmission channels and each of the reception channels in the 1 st module 1-1, thereby forming a virtual reception channel labeled with a reference numeral (4). Thereby, the antenna opening length of the 1 st module 1-1 virtually increases from D to 2D. In fig. 10B, 2Dsin θ is the phase difference between channels.
Up to this point, the reference number n is shown for the target candidate tgt The 1 st signal corresponding to the target candidate of (2) is subjected to discrete fourier transform according to the above formula (16), but is not limited thereto. For example, instead of discrete Fourier transform, fast Fourier transform (FFT; fast Fourier Transform), MUSIC (Multiple Signal Classification: multiple Signal Classification method), ESPRIT (Estimation of Signal Parameters via Rotational Invariance Technique: parameter estimation method by rotation invariant signal) or the like may be performed.
In the above equation (16), the far field is described, but if the opening is widened and the received wave cannot be approximated to a plane wave, the integration may be performed as a near field.
Fig. 11 is a flowchart showing detailed processing of step ST5 of fig. 4. Later, for the 3 rd module 3-n TxEx Transmitting transmit RFThe case of the signal is explained.
In 3 rd Module 3-n TxEx In the 3 rd local oscillation signal generation section 3-6-n TxEx A 3 rd local oscillation signal is generated (step ST1 d). The 3 rd local oscillator signal is synchronized with the 1 st local oscillator signal. In FIG. 1, n TxEx 1.
Code modulation section 3-5-n TxEx For the 3 rd local oscillation signal generating part 3-6-n TxEx The generated 3 rd local oscillation signal is code-modulated (step ST2 d). In the code modulation process, the code modulation sections 3-5-n TxEx Adding a code to the 3 rd local oscillation signal, thereby generating a 3 rd block 3-n TxEx The transmission channel number n of (2) Tx Transmit RF signal Tx in a transmit channel of (a) 3,nTxEx (h,t)。
Transmitters 3-3-n TxEx The slave code modulating section 3-5-n TxEx The input transmission RF signal is output to the antennas 3-2-n TxEx . Antennas 3-2-n TxEx The RF signal is transmitted to the space radiation (step ST3 d). In fig. 1, an antenna 3-2-1 transmits RF signals to space radiation.
Here, for the 1 st module 1-n MDL And 3 rd module 3-n TxEx The transmission timing of the transmission RF signal of (a) will be described.
FIG. 12A is a diagram showing the transmission channel number n of the 1 st module 1-1 Tx A diagram of transmission timings of transmission RF signals in a transmission channel of=1. FIG. 12B is a diagram showing the transmission channel number n of the 1 st module 1-1 Tx A diagram of transmission timings of transmission RF signals in a transmission channel of=2. In step ST1 in fig. 4, the 1 ST transmitting unit 10 of the 1 ST module 1-1 uses the transmission channel number n at the transmission timing shown in fig. 12A and 12B, for example Tx Antenna 1-2-1 corresponding to=1 transmits a transmission RF signal using transmission channel number n Tx The antenna 1-2-2 corresponding to=2 transmits a transmission RF signal. The 1 st module 1-1 alternately transmits the transmission RF signal in a time-division manner, thereby forming a transmission waveform having a high orthogonality of the transmission RF signal as shown in fig. 12A and 12B. Further, the code modulation section 1-5-1 is associated with the transmission channel number n Tx Transmission RF signal corresponding to=1 and transmission channel number n Tx The transmitted RF signals corresponding to =2 are modulated differently, thereby interfering with the waveThe inhibition performance is improved.
Fig. 12C is a diagram showing transmission timings of the transmission RF signals of the 3 rd module 3-1. Fig. 12D is a diagram showing transmission timings of the transmission RF signals of the 3 rd module 3-2. In fig. 12C and 12D, the number N of transmission channels in the 3 rd transmission unit 30 Tx,nTxEx 1, number of modules n TxEx 2. In step ST5 of fig. 4, the 3 rd transmitting unit 30 of the 3 rd module 3-1 transmits the transmission RF signal using the antenna 3-2-1 at the transmission timing shown in fig. 12C, for example. Next, the 3 rd transmitting unit 30 of the 3 rd module 3-2 transmits the transmission RF signal using the antenna 3-2-1 at the transmission timing shown in fig. 12D, for example. In this way, the 3 rd module 3-1 and the 3 rd module 3-2 alternately transmit the transmission RF signal in a time-division manner, and thereby, as shown in fig. 12C and 12D, become transmission waveforms with high orthogonality of the transmission RF signal. Further, the code modulation sections 3-5-n TxEx By performing different code modulation between the 3 rd module 3-1 and the 3 rd module 3-2, the suppression performance of the interference wave is improved.
In fig. 12A to 12D, the case where 4 transmission RF signals are transmitted in a time division manner is shown, but the 1 st transmission unit 10 and the 3 rd transmission unit 30 may transmit a plurality of transmission RF signals in a code division manner. In this case, the transmission RF signal is transmitted simultaneously after being a signal which can be separated by code modulation. However, the cross correlation of the received signals spreads in the speed direction of the target, and therefore, a sufficient linear frequency modulation number is required. In fig. 12A to 12D, the case where 4 transmission RF signals are transmitted in a time division manner is shown, but the 1 st transmission unit 10 and the 3 rd transmission unit 30 may transmit a plurality of transmission RF signals in a frequency division manner. In this case, the transmission RF signals are transmitted simultaneously after being signals using frequency bands that can be separated from each other. In addition, as a method of separating a plurality of transmission RF signals, time division, code division, and frequency division may be appropriately combined and used.
FIG. 13A is a block diagram showing the 1 ST block 1-n in step ST6 of FIG. 4 MDL Is a flowchart of the process of (1). From 3 rd module 3-n TxEx The transmission RF signal radiated to the space is reflected by a target existing in the space to become a reflected RF signal a. Reflected RF signal A is incident on 1 st module 1-n MDL Has a 1 st receiving part11 antenna 1-7-n Rx,nMDL . Antennas 1-7-n Rx,nMDL The incident reflected RF signal a is received (step ST1 e). By antennas 1-7-n Rx,nMDL The received reflected RF signal A as 1 st module 1-n MDL Is received on channel n of (2) Rx,nMDL Is output to the receivers 1-8-n Rx,nMDL 。
Receivers 1-8-n Rx,nMDL The received RF signal is down-converted using the 1 ST local oscillator signal (step ST2 e). Then, the receivers 1-8-n Rx,nMDL The down-converted signal is filtered using a band filter, the intensity of the signal passing through the band filter is amplified, and then phase detection is performed. By these processes, the 1 st module 1-n is generated MDL Is the reception channel number n of (2) Rx,nMDL A reception beat signal in a reception channel of (a). Receiving beat signals from receivers 1-8-n Rx,nMDL Outputs to A/D converters 1-9-n Rx,nMDL 。
A/D converters 1-9-n Rx,nMDL 1 st module 1-n MDL Is the reception channel number n of (2) Rx,nMDL The reception beat signal in the reception channel of (2) is converted from an analog signal to a digital signal, thereby generating a reception beat signal V 1,nMDL (3,n Tx ,n Rx H, m) (step ST3 e). Receiving beat signal V 1,nMDL (3,n Tx ,n Rx H, m) is 1 st module 1-n MDL Is the reception channel number n of (2) Rx,nMDL The 3 rd reception beat signal in the reception channel of (a). To illustrate the use of the slave 3 rd module 3-n TxEx The 3 rd reception beat signal is generated from the reflected RF signal of the transmitted RF signal, and the reception beat signal V represented by the above formula (12) is used 1,nMDL (n Tx ,n Rx H, m) is denoted as the reception beat signal V 1,nMDL (3,n Tx ,n Rx ,h,m)。
FIG. 13B is a block diagram showing the 2 nd block 2-n in step ST6 of FIG. 4 RxEx Is a flowchart of the process of (1). From 3 rd module 3-n TxEx Reflected RF signal A of transmitted RF signal radiated to space is incident on the 2 nd module 2-n RxEx Antennas 2-7-n in the 2 nd receiving unit 20 Rx,nRxEx . Antennas 2-7-n Rx,nRxEx Receiving incident reflected RFSignal a (step ST1 f). By antennas 2-7-n Rx,nRxEx The received reflected RF signal A as module 2-n of module 2 RxEx Is received on channel n of (2) Rx,nRxEx Is output to the receiver 2-8-n Rx,nRxEx 。
Receivers 2-8-n Rx,nRxEx The received RF signal is down-converted using the 2 nd local oscillator signal (step ST2 f). Then, the receivers 2-8-n Rx,nRxEx The down-converted signal is filtered using a band filter, the intensity of the signal passing through the band filter is amplified, and then phase detection is performed. By these processes, the 2 nd module 2-n is generated RxEx Is the reception channel number n of (2) Rx,nRxEx A reception beat signal in a reception channel of (a). Receiving beat signals from receivers 2-8-n Rx,nRxEx Output to A/D converter 2-9-n Rx,nRxEx 。
A/D converter 2-9-n Rx,nRxEx Module 2 to n RxEx Is the reception channel number n of (2) Rx,nRxEx The reception beat signal in the reception channel of (2) is converted from an analog signal to a digital signal, thereby generating a reception beat signal V 2,nRxEx (3,n Tx ,n Rx H, m) (step ST3 f). Receiving beat signal V 2,nRxEx (3,n Tx ,n Rx H, m) is module 2, 2-n RxEx Is the reception channel number n of (2) Rx,nRxEx The 2 nd reception beat signal in the reception channel of (a). To show the first module 2-n RxEx Using slave 3 rd modules 3-n TxEx The 2 nd reception beat signal is generated from the reflected RF signal of the transmitted RF signal, and the reception beat signal V represented by the above formula (12) is used 1,nMDL (n Tx ,n Rx H, m) is denoted as the reception beat signal V 2,nRxEx (3,n Tx ,n Rx ,h,m)。
Fig. 14 is a flowchart showing detailed processing of step ST7 and step ST8 of fig. 4. In the 1 st signal processor 12, the 1 st separating section 120 separates from the A/D converters 1-9-n Rx,nMDL Input of the 1 ST module 1-n obtained in step ST3e of FIG. 13A MDL Is the reception channel number n of (2) Rx,nMDL Reception beat signal V in reception channel of (a) 1,nMDL (3,n Tx ,n Rx H, m). 1 st separation part120 receives the beat signal V in the same manner as in the above equation (13) 1,nMDL (3,n Tx ,n Rx H, m) to demodulate. The demodulated received beat signal is separated into 3 rd blocks 3-n TxEx Each of the transmission channels and 1 st module 1-n MDL The signal of the channel is received (step ST1 g). Thereby, the 3 rd module 3-n is generated TxEx Transmission channel number n in (a) Tx,nTxEx And 1 st module 1-n MDL In the reception channel number n Rx Corresponding 3 rd reception beat signal V 1,nMDL,C (3,n Tx ,n Rx ,h,m)。
Next, the 1 st signal generating unit 121 uses the 3 rd reception beat signal V 1,nMDL,C (3,n Tx ,n Rx H, m), according to the number n based on the target candidate tgt Speed interval number q corresponding to the speed of the target candidate of (2) ntgt And with the target candidate number n tgt Distance interval number k corresponding to the distance of the target candidate of (2) ntgt Is based on the following expression (19) of the target candidate number n tgt Distance and velocity of target candidate of 3 rd signal f b,1,nMDL (3,n Tx ,n Rx ,q ntgt ,k ntgt ) (step ST2 g). 3 rd signal f b,1,nMDL (3,n Tx ,n Rx ,q ntgt ,k ntgt ) The 1 st signal generating unit 121 outputs the signal to the 2 nd coherent integration unit 125.
Figure GDA0003160005870000231
In the 2 nd signal processor 21, the 2 nd separating section 210 separates from the A/D converter 2-9-n Rx,nRxEx The 2 nd module 2-n obtained in step ST3f of FIG. 13B is inputted RxEx Is the reception channel number n of (2) Rx,nRxEx Reception beat signal V in reception channel of (a) 2,nRxEx (3,n Tx ,n Rx H, m). The 2 nd separation unit 210 receives the beat signal V in the same manner as the above (13) 2,nRxEx (3,n Tx ,n Rx H, m) to demodulate. The demodulated received beat signal is separated into 3 rd blocks 3-n TxEx Each of the transmission channels and the 2 nd module 2-n RxEx The signal of the channel is received (step ST1 g-1). Thus, the 3 rd module 3-n is generated TxEx Transmission channel number n in (a) Tx,nTxEx And module 2-n RxEx In the reception channel number n Rx,nRxEx Corresponding 2 nd reception beat signal V 2,nRxEx,C (3,n Tx ,n Rx ,h,m)。
Next, the 2 nd signal generating section 211 uses the 2 nd reception beat signal V 2,nRxEx,C (3,n Tx ,n Rx H, m), according to the number n based on the target candidate tgt Speed interval number q corresponding to the speed of the target candidate of (2) ntgt And with the target candidate number n tgt Distance interval number k corresponding to the distance of the target candidate of (2) ntgt Is based on the following expression (20) of the target candidate number n tgt Distance and velocity of target candidate of (2) signal f b,2,nRxEx (3,n Tx ,n Rx ,q ntgt ,k ntgt ) (step ST2 g-1). Signal 2 f b,2,nRxEx (3,n Tx ,n Rx ,q ntgt ,k ntgt ) The 2 nd signal generator 211 outputs the 2 nd coherent integration unit 125 of the 1 st signal processor 12.
The target candidate detecting unit 123 is configured to detect a target candidate, and therefore, can be limited to the target candidate number n tgt Speed interval number q ntgt And distance interval number k ntgt The corresponding signals are calculated, so that the calculation amount is reduced, and the radar device with reduced cost can be obtained. For example, the amount of computation of performing the fast fourier transform in the hit direction for the signals corresponding to all the distance section numbers M is M (H/2) log 2 H, calculation shown in the following formula (20) and target candidate number n tgt Distance interval number k of target candidate of (2) ntgt Corresponding speed interval number q ntgt The calculated amount of the signal is HN tgt Thus, M (H/2) log 2 H＞＞HN tgt . Further, the output is limited to the target candidate number n tgt Speed interval number q of target candidate of (2) ntgt And distance interval number k ntgt Is the 2 nd signal f b,2,nRxEx (3,n Tx ,n Rx ,q ntgt ,k ntgt ) Therefore, the traffic can be reduced, and the scale of the radar apparatus can be reduced.
Figure GDA0003160005870000241
The 2 nd coherent integration section 125 is directed to the 2 nd signal f generated by the 2 nd signal processor 21 b,2,nRxEx (3,n Tx ,n Rx ,q ntgt ,k ntgt ) And the 3 rd signal f generated by the 1 st signal generating unit 121 b,1,nMDL (3,n Tx ,n Rx ,q ntgt ,k ntgt ) The coherent integration is performed according to the following equation (21) based on the arrival phase difference corresponding to the arrival angle candidate of the target candidate (step ST3 g). By performing this coherent integration, the target candidate number n is generated tgt Target candidate related signal R of (2) 3,ch (n θ ,q ntgt ,k ntgt ). However, the 2 nd coherent integration unit 125 uses the target candidate number n when there is an influence of the target movement, which is the doppler frequency between the transmission module and the transmission channel tgt Speed interval number q of target candidate of (2) ntgt After suppressing the influence of the velocity, the process of the following formula (21) is performed.
Figure GDA0003160005870000251
In the above formula (21), N θ Is the number of hypothetical target angles, n θ Is a target angle number assigned to the virtual target angle.
Figure GDA0003160005870000252
Is with the target angle number n θ The 3 rd module 3-n related to the target angle TxEx Transmission channel of (1) and 1 st module 1-n MDL Is a phase difference of the reception channels of (a). />
Figure GDA0003160005870000253
Figure GDA0003160005870000254
Is with the target angle number n θ 1 st module 1-n related to target angle of (c) MDL Is the reception channel number n of (2) Rx,nMDL Incoming phase differences in the receive channels of (a). />
Figure GDA0003160005870000255
Is with the target angle number n θ The 3 rd module 3-n related to the target angle TxEx Transmission channel and 2 nd module 2-n RxEx Is a phase difference of (a) and (b). />
Figure GDA0003160005870000256
Is with the target angle number n θ The 2 nd module 2-n related to the target angle of (2) RxEx Is the reception channel number n of (2) Rx,nRxEx Incoming phase differences in the receive channels of (a). />
Up to this point, the reference number n is shown for the target candidate tgt The 2 nd and 3 rd signals corresponding to the target candidates of (2) are subjected to discrete fourier transform according to the above formula (21), but the present invention is not limited thereto. For example, FFT, MUSIC, ESPRIT, or the like may be performed instead of discrete fourier transform.
In the above equation (21), the far field is described, but if the opening is widened and the received wave cannot be approximated to a plane wave, the integration may be performed as the near field.
Showing the number n for candidate with target tgt The 2 nd and 3 rd signals corresponding to the target candidates of (2) are subjected to discrete fourier transform according to the above formula (21), but may further include a number n corresponding to the target candidate tgt The 1 st signal corresponding to the target candidate of (c) is integrated. Thus, side lobes and grating lobes can be reduced.
3 rd Module 3-n TxEx May also have a receive channel. That is, the 3 rd module 3-n TxEx May also be the same as the 1 st module 1-n MDL The modules transmitting and receiving are performed identically.
The angle calculation unit 126 calculates the number n according to the target candidate tgt Is related to target candidate of (a)Number R 3,ch (n θ ,q ntgt ,k ntgt ) Calculating the target candidate number n tgt Angle candidate n 'among target candidates of (a)' θ,tgt (step ST4 g). With angle candidate n' θ,tgt Corresponding angle θ (n' θ,tgt ) The output from the angle calculation unit 126 is to the display 9. The display 9 displays the target candidate number n on the screen tgt Speed, distance, and angle of target candidates of (a).
At a target angle θ and a target angle number n θ Target angle θ 'of (2)' nθ In the case of coincidence, with the target candidate number n tgt Target candidate related signal R of (2) 3,ch (n θ ,q ntgt ,k ntgt ) The signal power shows a maximum value by coherent integration. I.e. for the 3 rd module 3-n TxEx Each of the transmission channels and 1 st module 1-n MDL Is a signal of each receiving channel of the 3 rd module 3-n TxEx Each of the transmission channels and 2 nd module 2-n RxEx The signal of each of the reception channels is coherently integrated, whereby the power of the coherently integrated signal increases. By using this signal, a radar device with improved detection performance of an object can be obtained.
Fig. 15A is a diagram showing an actual antenna configuration in the radar apparatus of embodiment 1. Fig. 15B is a diagram showing an actual antenna configuration and a virtual antenna configuration in the radar apparatus according to embodiment 1. In FIG. 15A, the 3 rd module 3-1, the 2 nd module 2-1, the 1 st module 1-1, the 2 nd module 2-2 and the 3 rd module 3-2 are arranged in a straight line in this order. When the antenna opening length corresponding to each of the reception channels of the 2 nd module 2-1, the 1 st module 1-1 and the 2 nd module 2-2 is set to D, the antenna opening length corresponding to the reception channel (1 a) of the entire radar apparatus becomes 3D. In fig. 15A, 3Dsin θ is the phase difference between channels.
The 1 st signal processor 12 is according to the 3 rd module 3-n TxEx 1 st module 1-n of each transmission channel of (1) MDL 3 rd module 3-n TxEx Each of the transmission channels and 2 nd module 2-n RxEx Coherently integrating the signal, thereby forming a signal with the symbol in fig. 15BVirtual reception channel denoted by reference numeral (2 a). Thereby, the antenna opening length of the radar apparatus of embodiment 1 virtually increases from 3D to 6D. In fig. 15B, 6Dsin θ is the phase difference between channels.
Fig. 16 is a diagram showing a relationship between the angle of the target candidate and the power of the signal corresponding thereto in the case where the number of target candidates is 1. In fig. 16, a curve (a) shows the relationship between the power of a signal transmitted and received by the 1 st module 1-1 shown in fig. 10A and the angle of a target candidate calculated using the signal. Since no coherent integration is performed, the antenna aperture length remains D, and the angular resolution is low as seen from the curve (a).
Curve (b) shows the relationship between the power of a signal obtained by coherent integration between channels shown in fig. 9 and the angle of a target candidate calculated using the signal in the 1 st module 1-1 in which the transmission channels are 2 and the reception channels are 1. In this case, as shown in fig. 10B, since the virtual reception channel is added and the antenna aperture length is 2D, the angular resolution of the curve (B) is improved compared to the curve (a). However, sufficient angular resolution is not obtained.
Curve (c) shows the relationship of the power of a signal obtained by coherently integrating signals according to each transmission channel of the 3 rd module 3-1 or 3-2, each reception channel of the 1 st module 1-1, and each reception channel of the 2 nd modules 2-1 to 2-4, and the angle of a target candidate calculated using the signal. In the radar apparatus shown in fig. 2, the 1 st module 1-1 and the 2 nd modules 2-1 to 2-4 receive signals transmitted from the 3 rd module 3-1 or 3-2, respectively, and this relationship is obtained. By performing coherent integration of the signal between the modules and between the channels, the angular resolution is significantly improved.
Fig. 17 is a diagram showing a relationship between the angle of the target candidate and the power of the signal corresponding thereto in the case where the number of target candidates is 2. In fig. 17, a curve (a 1) shows a relationship between the power of a signal obtained by coherent integration between channels shown in fig. 9 and a target angle calculated using the signal in the 1 st module 1-1 in which the transmission channels are 2 and the reception channels are 1. Further, curves (b 1) and (b 2) are the results of processing the signal obtained by coherent integration for each target. From the curves (a 1), (b 1) and (b 2), it is clear that, in the 1 st module 1-1 alone, even if there are 2 targets, sufficient angular resolution cannot be obtained, the respective targets cannot be separated, and angle measurement cannot be performed.
Curve (c 1) shows the relationship of the power of a signal obtained by coherently integrating signals according to each transmission channel of the 3 rd module 3-1 or 3-2, each reception channel of the 1 st module 1-1, and each reception channel of the 2 nd modules 2-1 to 2-4, and the angle of a target candidate calculated using the signal. In the radar apparatus shown in fig. 2, the 1 st module 1-1 and the 2 nd modules 2-1 to 2-4 receive signals transmitted from the 3 rd module 3-1 or 3-2, respectively, and this relationship is obtained. By using these modules, 2 targets are separated separately, enabling angle measurement.
The radar apparatus according to embodiment 1 can detect a target with a small reflected power by suppressing phase noise. As is clear from the curve (c 1) shown in fig. 17, the radar apparatus according to embodiment 1 obtains angular resolution which cannot be achieved only in the 1 st block 1-1. Thus, a radar device with improved target detection performance can be obtained.
In the description so far, a linear array composed of a plurality of modules is shown, but is not limited thereto. For example, antennas corresponding to the transmission channel and the reception channel may be arranged differently in the vertical direction or the horizontal direction, or in the vertical direction and the horizontal direction. In this case, the radar apparatus according to embodiment 1 may calculate only the angle of the target in the horizontal plane, calculate only the elevation angle of the target, or calculate the angle of the target with respect to the horizontal plane and the vertical direction.
Next, the usefulness of the radar apparatus according to embodiment 1 will be described.
The radar apparatus according to embodiment 1 can be configured to disperse the 1 st, 2 nd and 3 rd modules, and thus can cope with the constraint that a plurality of modules cannot be collectively configured. In addition, the radar apparatus of embodiment 1 uses the 1 st, 2 nd, and 3 rd modules, whereby a wide antenna opening which cannot be achieved in only the 1 st module can be obtained. Thereby, the angular resolution of the target is improved.
Fig. 18A is a diagram showing an outline of a conventional radar apparatus in which a plurality of modules use the same local oscillation signals. The conventional radar apparatus shown in fig. 18A includes modules 150 to 153. The module 150 has a transmitting section 150a and a local oscillation generator 150b. The module 151 has a receiving portion 151a, the module 152 has a receiving portion 152a, and the module 153 has a transmitting portion 153a. The local oscillation signal generator 150b distributes the same local oscillation signal to the plurality of modules 150 to 153, respectively. In this configuration, when the number of allocations increases, the power of the local oscillator signal decreases accordingly. Therefore, the local oscillation signal generator 150b needs to be a large-scale device for compensating the distribution loss of the local oscillation signal, and the cost increases.
Fig. 18B is a diagram showing an outline of a conventional radar apparatus in which a plurality of modules use different local oscillation signals, respectively. The conventional radar apparatus shown in fig. 18B includes modules 160 to 163. The module 160 has a transmitting section 160a and a local oscillation signal generator 160b. The module 161 has a receiving unit 161a and a local oscillation generator 161b, the module 162 has a receiving unit 162a and a local oscillation generator 162b, and the module 163 has a transmitting unit 163a and a local oscillation generator 163b. The local oscillation signal generators 160b to 163b generate local oscillation signals different from each other. Thus, phase noise increases.
Fig. 18C is a diagram showing an outline of the radar apparatus according to embodiment 1. As shown in fig. 18C, in the radar device according to embodiment 1, the 1 st module 1-1 and the 2 nd modules 2-1 to 2-N RxEx And 3 rd modules 3-1 to 3-N TxEx Since the local oscillation signal generating sections are provided, distribution loss of local oscillation signals is reduced. Further, by using the same local oscillation signal for transmission and reception, the influence of phase noise is suppressed, and even a target with a small reflected power can be detected.
Fig. 19A is a diagram showing a relationship between the power of a signal corresponding to a target and the distance of the target, which is measured by a conventional radar apparatus. In fig. 19A, a curve A1 shows a relationship between the power of a received signal supposed for a target with a small reflected power and the distance from the target. Curve B1 shows the reception of a target with a large reflected power measured by the conventional radar apparatus shown in fig. 18B The power of the signal and the distance to the target. The object with smaller reflected power exists around the object with larger reflected power. Threshold value
Figure GDA0003160005870000281
Is a threshold value of loss due to phase noise, and in a curve B1 showing a received signal corresponding to a target measured by a conventional radar apparatus, the loss due to phase noise is greater than the threshold +.>
Figure GDA0003160005870000282
The radar apparatus shown in fig. 18B includes a module 160 as a transmitting sub-array section and modules 161 and 162 as receiving sub-array sections. The plurality of receiving sub-array sections receive signals, and the transmitting sub-array section and the receiving sub-array section use different local oscillation signals. Therefore, in the radar apparatus shown in fig. 18B, as shown in fig. 19A, in the signal corresponding to the target having a large reflected power, the phase noise increases, and it is difficult to detect the target having a small reflected power existing in the periphery of the target. For this reason, in order to solve this problem, the radar apparatus shown in fig. 18B needs to synthesize the received signals of the plurality of receiving subarrays for each arrival angle of the target, and the amount of calculation for obtaining the angle of the target increases.
Fig. 19B is a diagram showing a relationship between the power of a signal corresponding to a target and the distance of the target, which is measured by the radar apparatus according to embodiment 1. In fig. 19B, a curve A1 shows a relationship between the power of a received signal supposed for a target with a small reflected power and the distance from the target. Curve B2 shows the relationship between the power of the received signal for the target with a large reflected power and the distance from the target, which is measured by the radar apparatus of embodiment 1.
Since the radar apparatus according to embodiment 1 uses the same local oscillation signal on the transmitting side and the receiving side, the loss due to phase noise is smaller than the threshold value as indicated by the arrow in the curve B2 showing the received signal corresponding to the target
Figure GDA0003160005870000291
The influence of phase noise is suppressed. This improves the detection performance of the target having a small reflected power, which is present around the target having a large reflected power. That is, in the radar apparatus according to embodiment 1, the antenna opening is virtually enlarged by using a plurality of modules using the same local oscillation signals on the transmitting side and the receiving side, and thus the influence of the phase noise of the reception beat signal is reduced, and therefore, the detection accuracy of the target can be ensured and the angular resolution of the target can be improved. In addition, since beam synthesis, that is, integration between reception channels is not required for all distance and speed sections before target detection, the amount of calculation for obtaining the angle of the target is reduced.
In order to suppress the influence of phase noise, it is necessary to increase the correlation of the local oscillation signal for transmission and the local oscillation signal for reception, that is, to reduce the difference of phase noise in down-conversion.
FIG. 20A is a schematic diagram showing the 1 st module 1-n MDL A graph of frequency versus time for transmission and reception of signals. In fig. 20A, a straight line C shows a relationship between the frequency and time of the local oscillation signal used in the 1 st transmission unit 10. The line D shows the relationship between the frequency of the local oscillation signal used in the 1 st reception unit 11 and time. The 1 st transmitting unit 10 transmits the transmission RF signal at time t=0, and the 1 st receiving unit 11 transmits the transmission RF signal at time t=2r max And/c receives the reflected RF signal. Here, c is the speed of light, R max Is the predetermined maximum detection distance in the radar apparatus of embodiment 1. In 1 st Module 1-n MDL Since the same 1 st local oscillation signal is used on the transmitting side and the receiving side, the local oscillation signals on the transmitting side and the receiving side are synchronized as shown in fig. 20A.
Fig. 20B is a graph showing the phase-time relationship between the 1 st local oscillation signal and the reflected RF signal received by the 1 st receiving section 11. In fig. 20B, a curve C1 shows the phase of the 1 st local oscillation signal versus time. The graph D1 shows the relationship between the phase of the reflected RF signal of the transmission RF signal transmitted by the 1 st transmission unit 10 and time. E1 is the phase noise difference between the 1 st local oscillator signal and the reflected RF signal.
Fig. 20C is a graph showing the phase versus time between the 2 nd local oscillation signal and the reflected RF signal received by the 2 nd receiving section 20. In fig. 20C, a curve C2 shows the phase of the 2 nd local oscillation signal versus time. The curve D2 shows the relationship between the phase of the reflected RF signal of the transmission RF signal transmitted by the 1 st transmission unit 10 and time, similarly to the curve D1 shown in fig. 20B. The 2 nd local oscillation in fig. 20C is a different local oscillation from the 1 st local oscillation. E2 is the phase noise difference between the 2 nd local oscillator signal and the reflected RF signal.
The following equation (22) shows the magnitude relationship between the difference between the phase noise of the 1 st local oscillation signal used by the 1 st transmitting unit 10 and the phase noise of the 1 st local oscillation signal used by the 1 st receiving unit 11, and the difference between the phase noise of the 1 st local oscillation signal used by the 1 st transmitting unit 10 and the phase noise of the 2 nd local oscillation signal used by the 2 nd receiving unit 20. In the following formula (22),
Figure GDA0003160005870000301
is 1 st module 1-n MDL The transmission channel number n of (2) Tx Phase noise of the 1 st local oscillation signal in the transmission channel. />
Figure GDA0003160005870000302
Is 1 st module 1-n MDL Is the reception channel number n of (2) Rx,nMDL Phase noise of the 1 st local oscillator signal in the reception channel. Furthermore, the->
Figure GDA0003160005870000303
Is the 2 nd module 2-n RxEx Is the reception channel number n of (2) Rx,nRxEx Phase noise of the 2 nd local oscillator signal in the receive channel.
Figure GDA0003160005870000304
In 1 st Module 1-n MDL In the 1 st transmitting unit 10 and the 1 st receiving unit 11, the same 1 st local oscillation signal is used in the 2 nd module 2-n RxEx The 2 nd receiving unit 20 uses a 1 st local oscillation signal2 local oscillation signals, in this case, as shown in fig. 20B and 20C, the phase noise difference E1 is smaller than the phase noise difference E2. The above equation (22) shows that the difference in phase noise when the 1 st transmission unit 10 and the 1 st reception unit 11 use the same 1 st local oscillation signal is smaller than the difference in phase noise when the 2 nd reception unit 20 uses a 2 nd local oscillation signal different from the 1 st local oscillation signal.
As shown in the above equations (10), fig. 20B and fig. 20C, there is a time difference 2R between the local oscillation signal and the received reflected RF signal max The farther the distance between the target and the radar apparatus, the larger the difference in phase noise, and the larger the influence of the phase noise.
1 st module 1-n MDL The 1 st local oscillation signal generation section 1-6-1, which suppresses phase noise in accordance with the relationship of the following expression (23), suppresses phase noise to a desired level or less as shown in fig. 19B. In the following formula (23),
Figure GDA0003160005870000305
is the allowable upper limit of the phase noise difference. The difference in phase noise is greater than +.>
Figure GDA0003160005870000306
In the case of (2), the influence of phase noise cannot be suppressed.
Figure GDA0003160005870000307
For example, when different local oscillation signals are used on the transmitting side and the receiving side, as shown on the right side of the above equation (22), the characteristics of the local oscillation signals are different on the transmitting side and the receiving side, and thus, the influence of phase noise cannot be suppressed, and the target detection performance is deteriorated. In addition, local oscillation signals different from each other can be adjusted so that the phase noise difference becomes
Figure GDA0003160005870000311
However, the cost increases due to the adjustment. Therefore, the 1 st local oscillation signal generation section suppresses phase noise in accordance with the relation of the above formula (23)1-6-1 has usefulness.
Further, the 1 st local oscillation signal generating section 1-6-1 uses the 1 st local oscillation signal in down-conversion of the reflected RF signal received by the 1 st receiving section 11, and also, according to loss caused by phase noise
Figure GDA0003160005870000312
By setting the radar parameters, desired phase noise can be suppressed. Namely, the 1 st local oscillation signal generating section 1-6-1 adjusts the modulation band B 0 Sampling frequency f s And a maximum detection distance R max Such radar parameters suppress phase noise such that the loss caused by the desired phase noise is +.>
Figure GDA0003160005870000313
Becomes the threshold value
Figure GDA0003160005870000314
The following is given.
For example, in order to satisfy the above expression (23), the 1 st local oscillation signal generating section 1-6-1 sets the modulation band B as radar parameters satisfying the following expression (24), the following expression (25), the following expression (26) and the following expression (27) 0 Sampling frequency f s And can be at a sampling frequency f s Distance R measured in disambiguated mode amb,fs . Here the number of the elements is the number,
Figure GDA0003160005870000315
is the loss caused by phase noise->
Figure GDA0003160005870000316
Threshold of f b,Rmax Is the maximum detection distance R max Beat frequency of>
Figure GDA0003160005870000317
Is the maximum detection distance R max Beat frequency f of (1) b,Rmax And sampling frequency f s Loss due to phase noise in the case of (a). The following (24) shows a modulation band B for enabling the 1 st local oscillation signal generation section 1-6-1 to satisfy desired performance 0 And sampling frequency f s Is a relationship of (3). The following (25) shows the maximum detection distance R for the 1 st local oscillation signal generation section 1-6-1 to satisfy the desired performance max And can be at a sampling frequency f s Distance R measured in disambiguated mode amb,fs Is a relationship of (3). The following (26) shows the maximum detection distance R for the 1 st local oscillation signal generation section 1-6-1 to satisfy the desired performance max Beat frequency f of (1) b,Rmax And sampling frequency f s Is a relationship of (3). The following formula (27) shows the loss caused by phase noise for the 1 st local oscillation signal generation section 1-6-1 to satisfy the desired performance +.>
Figure GDA0003160005870000318
Threshold of (2)
Figure GDA0003160005870000319
Distance from maximum detection R max Beat frequency f of (1) b,Rmax And sampling frequency f s Is a relationship of (3). The following (28) shows the maximum detection distance R for the 1 st local oscillation signal generation section 1-6-1 to satisfy the desired performance max Beat frequency f of (1) b,Rmax Distance from maximum detection R max Is a relationship of (3). The following (29) shows a sampling frequency f for enabling the 1 st local oscillation signal generation section 1-6-1 to satisfy desired performance s And can be at a sampling frequency f s Distance R measured in disambiguated mode amb,fs Is a relationship of (3).
As shown in the above equation (9), the radar apparatus according to embodiment 1 uses the 1 st local oscillation signal that is frequency-modulated to down-convert the reflected RF signal, as in the case of the transmission RF signal, and thus can set the sampling frequency f s Below modulation band B 0 。
In addition, in using modulation band B 0 The above sampling frequency f s In the case of (a), the correlation between the 1 st local oscillation signal and the reflected RF signal (the reflected signal of the 1 st transmission signal) from the target located at a distance equal to or greater than the distance resolution becomes low, and the influence of phase noise increases. Accordingly, the 1 st local oscillation signal generation section 1-6-1 reduces the sampling frequency f according to the following formula (24) s Setting radar parameters such thatThe correlation between the two signals becomes high, and thus, the signal can be suppressed from being located at the maximum detection distance R max The following targets are lost due to phase noise of the reflected RF signal.
B 0 >f s …(24)
R max <R amb,fs …(25)
f b,Rmax ≦f s …(26)
Figure GDA0003160005870000321
f b,Rmax ＝(2B 0 /cT 0 )R max …(28)
f s ＝(2B 0 /cT 0 )R amb,fs …(29)
Fig. 21 is a graph showing a relationship between a loss due to phase noise and a beat frequency. In fig. 21, the sampling frequency f s,H A higher sampling frequency, f, which does not satisfy the above formulas (26) and (27) s,L Is a lower sampling frequency that does not satisfy the above equation (26) and the above equation (27). As indicated by reference character Fa in fig. 21, the sampling frequency f s,H Beat frequency f at time b The above (26) is satisfied, but the above formula (27) is not satisfied. Thus, as shown by the two-dot chain line in fig. 21, the maximum detection distance R max Beat frequency f of (1) b,Rmax Loss due to phase noise at the time
Figure GDA0003160005870000322
Become the threshold value of loss caused by phase noise
Figure GDA0003160005870000323
The above. Thus, with the sampling frequency f s Becomes high, beat frequency f b As a result, there is a problem that the correlation between the 1 st local oscillation signal and the reflected RF signal (the reflected signal of the 1 st transmission signal) becomes low.
On the other hand, as shown by the one-dot chain line in fig. 21, the sampling frequency f is lowered s,L Beat frequency of timeRate f b Since the equation (27) is not satisfied but the equation (26) is satisfied, the correlation between the 1 st local oscillation signal and the reflected RF signal (the reflected signal of the 1 st transmission signal) is high.
The 1 st local oscillation signal generation section 1-6-1 sets the value of the radar parameter to a value in the region indicated by the reference symbol F in fig. 21 satisfying the above-mentioned expression (26) and the above-mentioned expression (27), whereby the loss due to the phase noise indicated by the reference symbol Fb in fig. 21 becomes a threshold value
Figure GDA0003160005870000324
The following equation (23) is satisfied. Thus, desired phase noise can be suppressed, and a radar device with improved or maintained target detection performance can be obtained.
Next, a module arrangement when the radar device according to embodiment 1 is mounted on a vehicle will be described. Next, the radar device according to embodiment 1 is provided with the 1 st module 1-1, the 2 nd modules 2-1 to 2-4 or 2-1 to 2-5 and the 3 rd modules 3-1, 3-2.
Fig. 22 is a diagram showing a 1 st configuration example of the 1 st module 1-1, the 2 nd modules 2-1 to 2-4 and the 3 rd modules 3-1, 3-2 for the vehicle 40. In the 1 st arrangement example shown in fig. 22, the 3 rd module 3-1, the 2 nd module 2-2, the 1 st module 1-1, the 2 nd module 2-3, the 2 nd module 2-4 and the 3 rd module 3-2 are arranged in a straight line in this order in the vicinity of the windshield of the vehicle 40.
Fig. 23 is a diagram showing a 2 nd configuration example of the 1 st module 1-1, the 2 nd modules 2-1 to 2-5 and the 3 rd modules 3-1, 3-2 for the vehicle 40. In the 2 nd arrangement example shown in fig. 23, the 1 st module 1-1 is arranged near the windshield of the vehicle 40, and the 3 rd module 3-1, the 2 nd modules 2-1 to 2-5 and the 3 rd module 3-2 are arranged in a straight line in this order in the bumper of the vehicle 40.
Fig. 24 is a diagram showing a 3 rd configuration example of the 1 st module 1-1, the 2 nd modules 2-1 to 2-5 and the 3 rd modules 3-1, 3-2 for the vehicle 40. In the 3 rd arrangement example shown in fig. 24, the 1 st module 1-1 is arranged in the front of the vehicle 40, and the 3 rd module 3-1, the 2 nd modules 2-1 to 2-5 and the 3 rd module 3-2 are arranged in a straight line in this order in the vicinity of the windshield of the vehicle 40.
Fig. 25 is a diagram showing a 4 th configuration example of the 1 st module 1-1, the 2 nd modules 2-1 to 2-4 and the 3 rd modules 3-1, 3-2 for the vehicle 40. In the 4 th configuration example shown in fig. 25, the 2 nd module 2-1, the 2 nd module 2-2, the 1 st module 1-1, the 2 nd module 2-3, and the 2 nd module 2-4 are arranged in a straight line in this order near the windshield of the vehicle 40. Further, the 3 rd module 3-1 and the 3 rd module 3-2 are disposed on a bumper of the vehicle 40.
Since the radar apparatus according to embodiment 1 has a high degree of freedom in module arrangement, a plurality of modules can be arranged in a distributed manner as shown in fig. 22, 23, 24, and 25. That is, the radar apparatus according to embodiment 1 can cope with the size of a vehicle or various arrangement places, as compared with a configuration in which all the modules are integrated. Further, the number of the respective modules can be set according to a desired specification, for example, according to an angular resolution.
Next, a hardware configuration of the radar apparatus according to embodiment 1 will be described.
1 st module 1-n MDL The 1 st transmitting unit 10, the 1 st receiving unit 11, and the 1 st signal processor 12, the 2 nd module 2-n RxEx Function of the 2 nd receiving part 20 and the 2 nd signal processor 21 and the 3 rd module 3-n TxEx The function of the 3 rd transmitting unit 30 in (a) is realized by a processing circuit. That is, the radar apparatus according to embodiment 1 includes a processing circuit for executing the processing of steps ST1 to ST8 shown in fig. 4. The processing circuit may be dedicated hardware or may be a CPU (Central Processing Unit: central processing unit) that executes a program stored in a memory.
Fig. 26A is a block diagram showing a hardware configuration for realizing the function of the radar apparatus of embodiment 1. Fig. 26B is a block diagram showing a hardware configuration of software that executes functions of the radar apparatus implementing embodiment 1. In fig. 26A and 26B, the antenna 100 is the antenna 1-2-n provided in the 1 st transmitting unit 10 Tx Antennas 1 to 7 to n provided in the 1 st receiving unit 11 Rx,nMDL Antennas 2-7-n provided in the 2 nd receiving unit 20 Rx,nRxEx Or the 3 rd transmitting unit 30 has the antennas 3-2-n Tx,nTxEx . The display 101 is the display 9 shown in fig. 1.
The input/output interface 102 is via a signal bus104 pairs of antennas 100 and transmitters 1-3-n Tx Receivers 1-8-n Rx,nMDL Receivers 2-8-n Rx,nRxEx Or transmitters 3-3-n Tx,nTxEx The signal exchange between them is relayed. In addition, the input-output interface 102 relays the exchange of signals between the display 101 and the 1 st signal processor 12 via the signal bus 104.
In the case where the processing circuit is the processing circuit 103 of dedicated hardware shown in fig. 26A, the processing circuit 103 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit: application specific integrated circuit), an FPGA (Field-Programmable Gate Array: field programmable gate array), or a component obtained by combining them. The 1 st module 1-n can be implemented with different processing circuits MDL The functions of the 1 st transmitting unit 10, the 1 st receiving unit 11, and the 1 st signal processor 12 in the above may be realized by using 1 processing circuit in a unified manner. Furthermore, the 2 nd module 2-n may be implemented with different processing circuits RxEx The functions of the 2 nd receiver 20 and the 2 nd signal processor 21 in the above-described configuration may be realized by using 1 processing circuit in a unified manner. Furthermore, the 3 rd module 3-n may be implemented using different processing circuits TxEx The functions of the 3 rd transmitting unit 30 in (a) may be realized by 1 processing circuit in a unified manner.
In the case where the processing circuit is the processor 105 shown in FIG. 26B, the 1 st module 1-n MDL The 1 st transmitting unit 10, the 1 st receiving unit 11, and the 1 st signal processor 12, the 2 nd module 2-n RxEx Function of the 2 nd receiving part 20 and the 2 nd signal processor 21 and the 3 rd module 3-n TxEx The function of the 3 rd transmitting unit 30 in (a) is realized by software, firmware, or a combination of software and firmware, respectively. In addition, the software or firmware is described as a program, and is stored in the memory 106.
The processor 105 reads out and executes the program stored in the memory 106, thereby realizing the 1 st modules 1 to n, respectively MDL The 1 st transmitting unit 10, the 1 st receiving unit 11, and the 1 st signal processor 12, the 2 nd module 2-n RxEx The function of the 2 nd receiver 20 and the 2 nd signal processor 21And 3 rd module 3-n TxEx The function of the 3 rd transmitting unit 30. For example, the functions of the respective modules have a memory 106, and the memory 106 stores a program that, when executed by the processor 105, results in execution of the processing of steps ST1 to ST8 in the flowchart shown in fig. 4. These programs cause the computer to execute the 1 st module 1-n MDL 2 nd Module 2-n RxEx And 3 rd module 3-n TxEx Is a step or a method of (a). The memory 106 may also be a memory storing a memory for causing a computer to function as the 1 st module 1-n MDL 2 nd Module 2-n RxEx And 3 rd module 3-n TxEx A computer-readable storage medium containing a program that functions.
The Memory 106 is, for example, a nonvolatile or volatile semiconductor Memory such as RAM (Random Access Memory: random access Memory), ROM (Read Only Memory), flash Memory, EPROM (Erasable Programmable Read Only Memory: erasable programmable Read Only Memory), EEPROM (Electrically-EPROM: electrically-erasable programmable Read Only Memory), a magnetic disk, a floppy disk, an optical disk, a high-density disk, a mini disk, a DVD, or the like.
With respect to 1 st module 1-n MDL The functions of the 1 st transmitting unit 10, the 1 st receiving unit 11, and the 1 st signal processor 12 in the above may be partially implemented by dedicated hardware, and partially implemented by software or firmware. For example, the 1 st transmitting unit 10 and the 1 st receiving unit 11 realize functions by using the processing circuit 103 as dedicated hardware, and the 1 st signal processor 12 reads out and executes programs stored in the memory 106 by the processor 105, thereby realizing functions. As such, the processing circuitry is capable of implementing the functions described above by hardware, software, firmware, or a combination thereof.
As described above, in the radar apparatus of embodiment 1, the 1 st module 1-1 generates a reception beat signal from the received reflected RF signal, the 2 nd module 2-1 generates a reception beat signal from the received reflected RF signal using the 2 nd local oscillator signal synchronized with the 1 st local oscillator signal, and the 1 st signal processor 12 calculates the angle of the target using a signal obtained by coherent integration based on the reception beat signal generated by the 1 st module 1-1 and the reception beat signal generated by the 2 nd module 2-1. Thus, the detection accuracy of the target can be ensured, and the angular resolution of the target can be improved.
In the radar apparatus according to embodiment 1, the 1 st module 1-1 has a plurality of transmission channels and a plurality of reception channels. The 1 st signal processor 12 performs coherent integration based on the phase difference between the channels. The 3 rd module 3-1 performs coherent integration based on an arrival phase difference generated based on the positional relationship of the 1 st module 1-1 and the 2 nd module 2-1. By performing these integrations, the detection accuracy of the target can be ensured, and the angular resolution of the target can be improved.
In embodiment 1, the use of the 1 st module 1 to n is shown MDL Detecting target candidates using module 2-n RxEx And 3 rd module 3-n TxEx The radar apparatus that improves the angular resolution of the target is not limited thereto. For example, the radar apparatus may have only the 1 st module 1-n MDL And module 2-n RxEx It is also possible to have only the 1 st module 1-n MDL And 3 rd module 3-n TxEx . Furthermore, the 1 st module 1 to n may be MDL And 2 nd module 2-n RxEx And the received signals of the target are synthesized, so that the angular resolution of the target is further improved.
Embodiment 2
Fig. 27 is a block diagram showing the structure of the radar apparatus according to embodiment 2. Unlike the radar apparatus of embodiment 1, the radar apparatus of embodiment 2 does not include the 2 nd module 2-n RxEx As shown in FIG. 27, the structure is provided with 1 st module 1-n MDL 3 rd Module 3-n TxEx And a display 9.
Fig. 28 is a flowchart showing the operation of the radar apparatus according to embodiment 2, and shows a signal processing method of the radar apparatus according to embodiment 2.
First, 1 st Module 1-n MDL The 1 ST transmission unit 10 transmits RF signals to the space by radiation (step ST1 h). When an object exists in space, the transmitted RF signal is reflected by the object and returned to the radar apparatus. 1 st module 1-n MDL The 1 ST receiving unit 11 receives the reflected RF signal of the transmission RF signal, and generates a reception beat signal from the reflected RF signal using the 1 ST local oscillation signal (step ST2 h). The joint is connected withThe beat signal is the 1 st received signal for detecting the target.
Next, the 1 st signal processor 12 generates a 1 st block 1-n based on the received beat signal inputted from the 1 st receiving unit 11 MDL The 1 st signal of the distance and speed of the target candidate for each transmit channel and each receive channel. The 1 ST signal processor 12 performs incoherent integration on the generated 1 ST signal, and calculates the distance and speed of the target candidate from the intensity of the signal obtained by the incoherent integration (step ST3 h).
Next, the 1 st signal processor 12 targets the 1 st module 1-n associated with each target candidate MDL The 1 ST signal of each transmission channel and each reception channel is coherently integrated based on the arrival phase difference corresponding to the arrival angle candidate of the target candidate (step ST4 h).
Next, 1 st module 1-n MDL The 1 st transmission unit 10 transmits RF signals to the space. 3 rd Module 3-n TxEx The 3 rd transmitting unit 30 transmits RF signals to the space by radiation (step ST5 h). The transmission RF signal transmitted by the 3 rd transmission unit 30 is a 3 rd transmission signal.
1 st module 1-n MDL The 1 st receiving unit 11 receives the reflected RF signal of the transmission RF signal transmitted by the 1 st transmitting unit 10, and receives the reflected RF signal of the transmission RF signal transmitted by the 3 rd transmitting unit 30. Then, in the same step as in fig. 13A, the 1 st receiving unit 11 generates a 1 st reception beat signal from the reflected RF signal of the transmission RF signal transmitted from the 1 st transmitting unit 10 by using the 1 st local oscillation signal. Further, in the same step as in fig. 13A, the 1 ST reception unit 11 generates a 3 rd reception beat signal from the reflected RF signal of the transmission RF signal transmitted from the 3 rd transmission unit 30 (step ST6 h). The 1 st reception beat signal is a 1 st reception signal for calculating the angle of the target, and the 3 rd reception beat signal is a 3 rd reception signal for calculating the angle of the target.
The 1 ST signal processor 12 generates the 1 ST block 1-n based on the 1 ST reception beat signal in the same step as step ST1g and step ST2g of fig. 14 using the 1 ST reception beat signal MDL The 4 th signal of the distance and speed of the respective target candidates of each transmission channel and each reception channel. Further, the 1 st signal The processor 12 uses the 3 rd reception beat signal in the same steps as step ST1g and step ST2g of fig. 14 to generate the 3 rd block 3-n based TxEx Each of the transmission channels and 1 st module 1-n MDL A 3 rd signal of a distance and a speed of each target candidate of each receiving channel.
The 1 ST signal processor 12 performs coherent integration on the 3 rd signal and the 4 th signal of each target candidate based on the arrival phase difference corresponding to the arrival angle candidate of the target candidate in the same step as step ST3g of fig. 14 (step ST7 h). Finally, the 1 ST signal processor 12 calculates the angle of the target candidate using the signals obtained by coherent integration with respect to each target candidate (step ST8 h). Information about the angle of the target candidate calculated by the 1 st signal processor 12 is displayed on the display 9.
As described above, in the radar device according to embodiment 2, the 1 st module 1 to n MDL Using the 1 st local oscillator signal, according to the 1 st module 1-n MDL Reflected RF signal of transmitted RF signal and slave 3 rd module 3-n TxEx Reflected RF signals of the transmitted transmission RF signals generate reception beat signals, respectively. The 1 st signal processor 12 uses the data set consisting of 1 st modules 1-n MDL The target is detected by generating a reception beat signal based on the signal of the 1 st module 1-n MDL According to the 1 st module 1-n MDL Reception beat signal generated by reflected RF signal of transmitted RF signal and signal generated by 1 st module 1-n MDL According to the 3 rd module 3-n TxEx The angle of the target is calculated from a signal obtained by coherent integration of a reception beat signal generated from a reflected RF signal of the transmitted transmission RF signal. Thus, the detection accuracy of the target can be ensured, and the angular resolution of the target can be improved. In addition, the 1 st module 1-n is shown after target detection MDL And 3 rd module 3-n TxEx In the case of transmitting the transmission RF signal, however, only the 3 rd module 3-n may be used after the target detection TxEx The transmit RF signal is transmitted.
The present invention is not limited to the above embodiments, and any combination of the embodiments, any modification of the components of the embodiments, or any omission of the components of the embodiments may be performed within the scope of the present invention.
Industrial applicability
The radar device of the present invention can ensure the detection accuracy of a target and improve the angular resolution of the target, and therefore, can be used for example in an obstacle detection device for a vehicle.
Description of the reference numerals
1-1、1-n MDL : 1 st module; 1-1-1, 1-1-2: transmitting an RF signal; 1-2-1, 1-2-2, 1-7-1-7-N Rx,nMDL 、2-7-1～2-7-N Rx,nRxEx 3-2-1, 100: an antenna; 1-3-1, 1-3-2, 3-3-1: a transmitter; 1-4-1: a transmission switching unit; 1-5-1, 3-5-1: a code modulation section; 1-6-1: a 1 st local oscillation signal generation unit; 1-8-1-8-N Rx,nMDL 、2-8-1～2-8-N Rx,nRxEx : a receiver; 1-9-1-9-N Rx,nMDL 、2-9-1～2-9-N Rx,nRxEx : an A/D converter; 2-1 to 2-5, 2-n RxEx : a 2 nd module; 2-6-1: a 2 nd local oscillation signal generation unit; 3-1, 3-2, 3-n TxEx : a 3 rd module; 3-6-1: a 3 rd local oscillation signal generation unit; 9. 101: a display; 10: a 1 st transmitting unit; 11: a 1 st receiving section; 12: a 1 st signal processor; 20: a 2 nd receiving part; 21: a 2 nd signal processor; 30: a 3 rd transmitting unit; 40: a vehicle; 102: an input/output interface; 103: a processing circuit; 104: a signal bus; 105: a processor; 106: a memory; 120: a 1 st separation section; 121: a 1 st signal generation unit; 122: a non-coherent integration section; 123: a target candidate detection unit; 124: a 1 st coherent integration unit; 125: a 2 nd coherent integration unit; 126: an angle calculation unit; 150-153, 160-163: a module; 150a, 153a, 160a, 163a: a transmitting unit; 150b, 160b to 163b: a local oscillator signal generator; 151a, 152a, 161a, 162a: a receiving section; 210: a 2 nd separation part; 211: and a 2 nd signal generating unit.

Claims (24)

1. A radar apparatus, characterized in that the radar apparatus has:
a 1 st module for generating a 1 st transmission signal using a 1 st local oscillation signal, transmitting the 1 st transmission signal, receiving a reflected signal of the 1 st transmission signal, and generating a 1 st reception signal from the received reflected signal using the 1 st local oscillation signal;
A 2 nd module for receiving the reflected signal of the 1 st transmission signal, generating a 2 nd reception signal from the received reflected signal using a 2 nd local oscillation signal synchronized with the 1 st local oscillation signal; and
a signal processor that detects a target using the 1 st received signal, and for the target, calculates an angle of the target using a signal obtained by coherent integration based on the 1 st received signal and the 2 nd received signal.
2. The radar apparatus according to claim 1, wherein,
the signal processor generates a 1 st signal based on a distance and a speed using the 1 st received signal, detects the distance and the speed of the target according to a signal strength of the 1 st signal, and coherently integrates the detected distance and speed of the target based on the 1 st received signal and the 2 nd received signal.
3. The radar apparatus according to claim 2, wherein,
the signal processor determines a section number of a distance and a section number of a speed of the target from the signal strength of the 1 st signal, and coherently integrates the distances and the speeds corresponding to the section numbers based on the 1 st received signal and the 2 nd received signal.
4. The radar apparatus according to claim 2, wherein,
the signal processor performs coherent integration of the 1 st received signal and the 2 nd received signal based on an incoming phase difference generated based on a positional relationship between the 1 st module and the 2 nd module.
5. The radar apparatus according to claim 1, wherein,
the signal processor generates a 1 st signal based on a distance and a speed of the object using the received signal generated by the 1 st module, non-coherently integrates the 1 st signal, and detects the object from the intensity of the signal obtained by the non-coherent integration.
6. The radar apparatus according to claim 2, wherein,
the 1 st module has more than 1 transmission channel and more than 1 reception channel,
the signal processor coherently integrates the 1 st signal according to the phase difference between the channels.
7. The radar apparatus according to claim 1, wherein,
the radar apparatus has a 3 rd module having a function of transmitting a transmission signal, generates a 3 rd transmission signal using a 3 rd local oscillation signal synchronized with the 1 st local oscillation signal,
the 1 st module receives the reflected signal of the 3 rd transmission signal, generates a 3 rd reception signal according to the received reflected signal of the 3 rd transmission signal using the 1 st local oscillation signal,
The signal processor calculates an angle of the target for the target using a signal obtained by coherent integration based on the 2 nd received signal and the 3 rd received signal or based on the 2 nd received signal, the 3 rd received signal, and the 1 st received signal.
8. The radar apparatus according to claim 1, wherein,
the number of the 2 nd modules is more than 1.
9. The radar apparatus according to claim 7, wherein,
the number of the 3 rd modules is more than 1.
10. A radar apparatus, characterized in that the radar apparatus has:
a 1 st module for generating a 1 st transmission signal using a 1 st local oscillation signal, transmitting the 1 st transmission signal, receiving a reflected signal of the transmission signal, and generating a 1 st reception signal from the received reflected signal using the 1 st local oscillation signal;
a 3 rd module that generates a 3 rd transmit signal using a 3 rd local oscillator signal synchronized with the 1 st local oscillator signal; and
a signal processor that calculates an angle of the object,
the 1 st module receives the reflected signal of the 3 rd transmitted signal, generates a 3 rd received signal using the 1 st local oscillator signal,
the signal processor detects the target using the 1 st received signal, and calculates an angle of the target for the target using a signal obtained by coherent integration based on the 1 st received signal and the 3 rd received signal.
11. The radar apparatus according to claim 10, wherein,
the signal processor generates a 1 st signal based on a distance and a speed using the 1 st received signal, detects the distance and the speed of the target according to a signal strength of the 1 st signal, and coherently integrates the detected distance and speed of the target based on the 1 st received signal and the 3 rd received signal.
12. The radar apparatus according to claim 11, wherein,
the signal processor determines a section number of a distance and a section number of a speed of the target from the signal strength of the 1 st signal, and coherently integrates the distances and the speeds corresponding to the section numbers based on the 1 st received signal and the 3 rd received signal.
13. The radar apparatus according to claim 11, wherein,
the signal processor performs coherent integration of the 1 st received signal and the 3 rd received signal based on an incoming phase difference generated based on a positional relationship between the 1 st module and the 3 rd module.
14. The radar apparatus according to claim 10, wherein,
the signal processor generates a 1 st signal based on a distance and a speed of the object using the received signal generated by the 1 st module, non-coherently integrates the 1 st signal, and detects the object from the intensity of the signal obtained by non-coherently integrating.
15. The radar apparatus according to claim 11, wherein,
the 1 st module has more than 1 transmission channel and more than 1 reception channel,
the signal processor coherently integrates the 1 st signal according to the phase difference between the channels.
16. The radar apparatus according to claim 10, wherein,
the number of the 3 rd modules is more than 1.
17. The radar apparatus according to any one of claims 6, 8, 9, 15, 16,
the 1 st module uses the 1 st local oscillation signal to perform modulation for separating a plurality of transmission signals into respective transmission signals, and transmits the plurality of modulated transmission signals.
18. The radar apparatus according to claim 17, wherein,
the modulation is time division, code division, frequency division, time division and code division or frequency division and code division.
19. The radar apparatus according to claim 7 or 10, wherein,
the 3 rd module performs modulation for separating the plurality of transmission signals into the respective transmission signals using the 3 rd local oscillation signal, and transmits the plurality of transmission signals subjected to modulation.
20. The radar apparatus according to claim 19, wherein,
The modulation is time division, code division, frequency division, time division and code division or frequency division and code division.
21. The radar apparatus according to claim 1 or 10, wherein,
and the 1 st module sets radar parameters according to the loss caused by phase noise and generates the 1 st local oscillation signal.
22. A signal processing method for a radar apparatus, the radar apparatus comprising: a 1 st module for generating a 1 st transmission signal using a 1 st local oscillation signal, transmitting the 1 st transmission signal, and receiving a reflected signal of the 1 st transmission signal; a 2 nd module for receiving the reflected signal of the 1 st transmission signal; and a signal processor that calculates an angle of the object, wherein the signal processing method has the steps of:
the 1 st module generates a 1 st receiving signal according to the received reflected signal by using the 1 st local oscillation signal;
the 2 nd module generates a 2 nd receiving signal according to the received reflected signal by using a 2 nd local oscillation signal synchronous with the 1 st local oscillation signal; and
the signal processor detects the target using the 1 st received signal, and calculates an angle of the target for the target using a signal obtained by coherent integration based on the 1 st received signal and the 2 nd received signal.
23. A signal processing method for a radar apparatus, the radar apparatus comprising: a 1 st module for generating a 1 st transmission signal using a 1 st local oscillation signal, transmitting the 1 st transmission signal, receiving a reflected signal of the 1 st transmission signal, and generating a 1 st reception signal from the received reflected signal using the 1 st local oscillation signal; a 3 rd module that generates a 3 rd transmit signal using a 3 rd local oscillator signal synchronized with the 1 st local oscillator signal; and a signal processor that calculates an angle of the object, wherein the signal processing method has the steps of:
the 1 st module receives the reflected signal of the 3 rd transmitted signal and generates a 3 rd received signal by using the 1 st local oscillator signal; and
the signal processor detects the target using the 1 st received signal, and calculates an angle of the target for the target using a signal obtained by coherent integration based on the 1 st received signal and the 3 rd received signal.
24. The signal processing method according to claim 22 or 23, wherein,
and the 1 st module sets radar parameters according to the loss caused by phase noise and generates the 1 st local oscillation signal.
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